Pruning a naturally vigorous tree to an open center like that helps keep it much smaller and stimulates fruiting. I have also heard it described as pruning to a basket shape or vase. Trees like mangos and peaches can be kept much shorter with several competing leaders, it minimizes apical dominance. The Japanese have been masters of the art of pruning for centuries, if they can bonsai a redwood, I am reasonably sure that I can keep a VP productive between 15-20 feet indefinitely.
https://en.wikipedia.org/wiki/Apical_dominance My Dad's Valencia pride was out of control only a few years after planting, it was over 20 feet and growing fast. I topped the central leader(tallest main stem) and any other side branches at 10 feet in mid October 2015. All pruning cuts were made above outward or downward facing buds when possible. It only produced about 30 or so mangos before pruning. In 2016,The year after I topped it, it produced more than double the previous crop. It regrew to about 15 feet by the end of Summer 2016. Vigor was visibly reduced the first year after pruning.
After it cropped last year, I took out the central leader completely at its base, so the lower side branches are the new leaders. It is important to keep the new leaders competing so one doesn't regain apical dominance. It was at about 12 feet after pruning. This year it has set from 3 different blooms. The tree now puts more energy into fruiting. I have not pruned since after the crop was done last year and it has only gotten about 3 feet taller. That shows that vigor has been further reduced by removing the central leader.(the apex of the tree) The basic idea when making pruning cuts is to make cuts above a bud that is facing in the direction you want the new branch to grow.(usually not vertically unless you need to replace part of the inner canopy.) This makes the tree spread out rather than up. Every year the inner canopy branches will need to be topped and rotationally replaced every few years, but I bet I will be able to keep my Dad's tree indefinitely at a height such that all fruit are harvestable with a picking pole.... The tallest branches in late Summer might eventually reach 17-20 feet in a few more years, but the fruit should hang no higher than 15 feet. After the crop is done this year, I will prune it to about 12 feet. It looks like the vigor is reduced to the point where I will just need to do maintenance pruning back to about 12-15 or so feet yearly to keep its yearly maximum height in the high teens. I feel keeping a very vigorous tree semi-dwarfed is a reasonable compromise. If I had not pruned my Dad's tree I am sure it would be well over 30 feet by now. Pic is tree in 2016 before I took out the main central leader.
