First of all, I have an unknown variety. So I’m not sure if the answers to these questions are variety specific or not.
Many of the sources I’ve read say that you should have 2 buds per spur and that spurs should be about fist-width apart or 5 inches. That makes about 4 shoots or so per foot of canopy. With that being said, some questions come to mind.
Does that mean we intend to have two shoots per spur? In other words, does that mean we prune off secondary shoots arising from the two buds on the spurs?
Does that mean we prune off any basal shoots other than ones we intend to use as replacement spurs for next year (to keep spurs close to the cordon)?
Do we let said basal shoots (as described in question #2) carry fruit or do we prune off their fruit?
Bonus question: how many fruitful shoots would you advise for an unknown grapevine variety going into it’s 3rd year in 2021?