Well, after many pros and cons regarding the dip (not deep) watering technique, some practical facts from experience (please take it with a grain of salt):
- It works to eliminate water pockets right after transplanting (once);
- It works when slip potting and the rootball is compact (once in a while);
- It works when the plant was not barerooted and the substrates are very different in granular size and drainage- in this case is almost impossible to predict when the roots are going to penetrate the new soil; when watered, the water will drain faster through the new substrate and either the old soil will be too wet, or the new soil around it will be too dry; another consequence is the core base of the rootball (the "shin") never getting enough water, specially if the pot is deep.
In this last case, I water normally twice as much the (new) soil around the old soil, and dunk the pot every 15 days or so.
- It DOESN'T WORK as regular watering, and it doesn't save dried up trees.
- It is risky for pines, junipers and conifers in general.

SORRY!
A mistake: where I say "water pockets", please read "air pockets", here:
"- It works to eliminate water pockets right after transplanting (once);"