I think the key to homegrown is drafting. Drafting is a lot easier than before, but i think you really need a perennial allstar or above if you are going to sink investing time and effort in training. You need someone with decent skill set. I've used the transfer list to find trainees if there is a hole in my training group and my draft has not yielded a player i can work with. Anyone with atrocious in any category is generally going to get cut automatically, unless the deficit is something i think i can overcome. I use three person training and i tend to space trainees out (but a large part of that going to depend on the draft). Because i train for even skills, i dont mind playing my center at pg to get OD skills. I use an exceptional level trainer if i can afford it. Learn your elastic skills and effects. A player with high handling will yield more pops in OD and PA. It also seems to me that training PA skills does not lessen as your player ages, so that is something you can train later in a player than say OD or IS. if you want to read about training, join the Audacity of Hoop and Teams on the Rise!! federations and read all the old posts from a lot of great players in the game.
Regarding SB, I trained that in my last set of trainees to the proficient-prominent level because the admins had stated they had bumped its effect to counter the dominance of inside offense, but i have not see it a great amount of return for my investment. However, all three are in the top 20 for blocks in the league.