The way I recommend people to prune all varieties of trees is generally to prune as little as possible but to remove all branches more than a third the diameter of the trunk at point of attachment. Worry about permanent scaffolds after a trees first real crop and only top the tree when it exceeds the desired height.
Everything else depends on special needs of any given tree and variety. Liberty may benefit from cutting a third of last seasons growth back when trees are in bloom to encourage secondary branching. By delaying it until then encourages more growth further back on the branch compared to dormant pruning where all stimulation is created an inch or two back from the cut.
This pruning inspires fuller branches but also delays fruiting.
Some varieties need branch spreading- a few bear sooner if you choose your scaffolds early and open the tree up before it begins bearing- these are the highly vigorous “woody” one’s such as Fuji.
If I had more than one Liberty on a free standing rootstock I would graft other types on all but one tree and do it early. I prefer grafting over varieties from the trunk and older Liberties often only let you graft low in the tree outward from scaffolds. They don’t tend to send out vertical water sprouts from the trunk- even when you top them.