The picture was more to demonstrate the drop crotch prune technique.
Once your tree gets about 5 years old, regardless of whether you've been diligent about tipping new growth, you will have to begin the process cutting major limbs (2 inch+ diameter) if you want to keep the tree to a manageable height. If you do not, the tree will simply continue to grow and grow until it achieves terminal height. At that point your tree will not be in an optimal state of health and all your fruit will be at the outer edges of the canopy, so you end you with a large volume of wasted space underneath the canopy where light can no longer penetrate. To keep your tree to a desired height, you will cut out major limbs once a year. Once you cut away a major limb, light can again penetrate the canopy, and branches begin to form within the inner canopy. (Eventually you'll rotate around and in a few years cut those newly formed branches out when they have grown to become major limbs again.)
So, now that you see the reasoning behind removing major limbs, you need to know how to properly do it in a way that doesn't injure the tree. Most backyard gardeners and uncertified tree trimmers will use a 'heading cut'. The heading cut is where the trimmer chops a major limb without regard to proximity to a branch collar. This is bad, as the tree will dump out a bunch of water sprouts and will not be able to properly heal -- providing a weak point where parasites and disease can get in and eventually cause decay. Limbs that form after a heading cut are also usually weakly attached -- not a good thing in hurricane alley :-). (In California we referred to this type of 'pruning' as hat-racking, and it was illegal in many areas. Here in Tamarac, however, it's quite rare to see a properly pruned tree.)
In contrast to the heading cut, there's the proper way to prune a major limb, which is known as the drop crotch prune. The drop crotch pruning technique tries to make cuts either at a branch collar or a cut just above a limb that's at least 1/2 the size of the limb that's left behind. This type of cutting allows the tree to heal very well at the cut site. Trees can compartmentalize branch collars and close them off, sealing out infection. The other type of cut (where you leave a limb just below the cut) also allows the tree to seal off the cut site. (I think the reason for this is because the cambium is left in a highly active state and quickly 'donuts' over the cut.) Moreover, the tree doesn't go berzerk pushing out a bunch of water sprouts (that you have to go back and thin out).
For more info on drop crotch pruning, I highly recommend Gilmans 'Illustrated Guide to Pruning'. Dr Campbell uses drop crotch cuts in his pruning videos, but doesn't specifically speak to it. Believe it or not, he actually prunes all 500 or so mango trees at the Fairchild Farm himself!
This image illustrates the two types of drop crotch prune cuts referenced above. In the top cut, a large limb is left behind. The 2nd cut is made at a branch collar. Both are healthy cuts.
It looks sort of drastic to me...someone who has never really pruned until recently. I still don't quite get it. If I am interpreting the picture correctly, is about 1/2 of the new growth cut away?
Also, when would you start doing this-after 3 years? 5?
In the past, I never pruned my trees are all. I just used a tall ladder
I would LOVE to keep me trees at 15 feet- Valencia Pride is a really tasty mango but I know that the tree has the potential to get large. The Baileys Marvel also.