I'll try to explain how I think it is, trees dont heal a wound they seal it with Codit
Proper cuts while better are still a wound thats unexpected by the tree. In natural limb decline process's the tree begins it own symplast withdrawal and activation of Codit. When you cut a tree limb off the tree will attempt to seal compartmentalize the wound by the process of Codit as best it can given the injury's size location season species traits and the tree vigor etc etc .
but go back a few steps &
1st avoid the need or do it early in juvenile tree growth.
2nd if needed minimizes the wound size or do when tree response is better.
3rd more often no wound paint is needed and this has been proven. Thou I find in fruit trees in winter or slow growth time a dab of acrylic paint after time to allow the surface cell plugging and tannin oxidization may not harm and may just deter pathogen attention the rest is complex due to individuality of a trees response to wounds, so its your call from here
[video=youtube;v_ZF6MPGBzU]http://www.youtube.com/watch?v=v_ZF6MPGBzU[/video]