SteveM: Somewhat similar way of grafting is very nicely shown here (just without leaving the bark on the side). Grafting starts 13s into the video.
https://www.youtube.com/watch?v=hg-SCpkm_u8
After thinking about this I think I am going to take a young scaffold branch on an apple tree and cut it back by 1/3rd and graft a new variety to the end via w&t and then move back 3 to 4" and side graft a second variety. Since the cut is fresh there should be enough stimulant to push both grafts. In fact, instead of a side graft I might just try a dormant chip bud. That’s what makes grafting so cool. Lot of experimenting to be done.
I plan on grafting several varieties to this one branch so I’m letting it grow out, another excellent advantage of side grafting.
The host tree is one I picked up at a big box store about 10 years ago, I swear it was labeled Macintosh but it’s got some of the worst Red Delicious apples I’ve ever seen. The skins are thick leathery, and bitter, the flesh is astringent and green until cut, then it instantly turns brown. Oh wait, I think that describes most Red Delicious apples. Anyway, two years ago the orchard gods were smiling down and four water sprouts shot out evenly spaced around the trunk at about two feet off the ground. I’m taking advantage these shoots and turning this into a Frankentree, grafting every type of apple I want to try. So far it has 8 varieties grafted to it but I’m just getting started.
One thing I didn’t do that might have helped is notch cut the understock above graft after it calloused over.
Was out in the orchard and decided to take a closer look at some of the side grafts I did this spring. They all took and most put on 12-18" of growth. At first glance you might think they are t-buds but they all suffer from poor crotch angles as expected. Two in particular have put on tons of growth and really got away from me. The one I find most interesting is one I put on my 2nd leaf Franken-apple that some of you may remember was partially destroyed by storm damage a couple months back. At the time, I cleaned up the storm damage and figured I had nothing to lose by covering the wounds on the Franken-apple with pruning sealer and letting nature take its course. It seems to have recovered well. The side graft is the lower limb with blue string tying it down. You can see it’s grown so much it’s off the edge of the picture. Ignore the ugly shape of the tree. Haha. The storm damage really made the tree a wacky mess.
This pic shows a close-up of the graft union and the less than ideal crotch angle. I’ll let it mature and see if it survives.
Third pic shows another detailed look at the graft callusing on a side graft of Satsuma on Emerald Beaut. This graft grew prolifically as well. I would guess about 5 feet of growth. I pruned it back by half.
So even though the side graft is not very common or popular you can see they seem to take well. Long term is a different story. Instead of side grafting in spring I suppose budding that same area in summer and then notching above the bud the following spring would probably work better and allow for more preferred crotch angles. Only issue for me is that I suck at budding.
I miss that kind of graft for many years and doing very well, in fact it was my first graft, the correct name of this type of graft is “subcortical lateral graft”.
This type of graft is a good option to change variety a tree without destroying too, ie, we can make a graft on the trunk and if you grab it at 3 months cut above the tree and if our graft fails can keep 100 % of our tree and try next year.
I recommend you not watch the video of speedter1, and you see that this man is an inexperienced, anyone who has a little experience would wear cuttings fruit buds instead of using cuttings with flower buds, plus it does wrong.
Web site takes too long to upload the pictures, that is why I leave a link in Spanish and one in English, if you do not load photographs well wait a little or refresh the browser
http://www.jardin-mundani.com/empelts/lateralsubcortical.htm
if someone wants to see more grafts mundani, you can see them here (also brings compatibility list to see who supports whom)
http://www.jardin-mundani.com/empelts/INJERTOS.htm
I did a few side grafts 2 years ago. I didn’t know much then, so I did not top the tree above the graft. I inserted them on branches, not the trunk, and put 2 of them at good angles, I wish I had done them all at this angle.
Not cutting off the branch above the graft did seem to slow down the growth rate, but the resulting graft is solid. May be the slower growth allowed the graft to heal well. At any rate, this year( 2 years later) 3 of the 4 are producing apples and they seem to be holding up very well. That said, they do not have a heavy load, only 2 apples each. What will happen in later years, 
who knows???
I saw a new YouTube video recently that describes a type of side graft called a “double tongue side graft”. I had never seen this graft done before. It appears to be a nice alternative to a bark graft. And the lower tongue helps stabilize the graft. Chalk it up as one more type of graft to add to our arsenal’s.
Quite nice! Looks to be more suited to thicker scionwood too.
A very skillfully done graft. But what is the second (lower) tongue good for if you dont cut the corresponding part (the backside) of the scion? That would be to enlarge the area of cambium contact. but without that aditional cut in the scion I dont see the advantage of that second tongue in the stock.
It looks like, instead of bothering with flaps, they are just driving the point of the scion under lower flat to anchor the scion. The back of the scion should be already clean from the long cut. I think it’s primary purpose, though, is preventing slipping during wrapping.
I wondered about that as well. There would still be some additional cambium contact if the scion edges match the bottom slit. But I agree that if the grafter took a little extra off the outside face of the scion the additional cambium contact would help. They probably have a very high success rate so might not feel the additional cut is necessary. Maybe it weakens the wood enough to not warrant it. The bottom slit probably helps with stabilization of the graft more than anything.
They made the comment in the video that the second tongue in the stock was “instead of securing the scion with a nail”.
If you do that and if both grafts take, wouldn’t you have to get rid of one to make the other receive all the energy from the tree? Or is there enough to go around?
Hi @Susu in the last video posted the tree they cut back has a super-substantial root-system. Those branches grafted onto are quite thick; as especially compared to the scion.
That tree alone has a ton of growth push power so a graft or two (for insurance) could be place onto each limb.
You can think of it that if (2) grafts take on a single limb, then you’d have scionwood for the next year removing one and keeping the strongest. (You/me/anyone) may decide to keep the second graft on for a few years for more scionwood.
Many grafters place one, two, sometimes three grafts as bark grafts up high on a rootstock above the deer browsing point and later remove the others assuming all of their grafts were successful.
Dax
I think so but in truth I totally forgot to try that last year. I always have big intensions but in this case I had forgotten to even try it by the time grafting season came by. Aubrey I’ll try it this year if I remember
Thank you. I like the idea of having insurance. 
Good video!
Last spring I used the side grafts to add lower branches on a mature apple tree, 4 out of 5 took, probably need to provide some support as they grow this year for several years if I allow them to fruit.
Is the graft union on a side graft stronger sooner (to withstand birds, wind, etc) than a bark graft? I usually keep bark grafts splinted for support for a year. One advantage is you don’t have to wait for bark to slip to do side graft. Bark graft has more cambium contact though, seems to me.