25 minutes will help them catch up so they will be playable sooner, but I would only put that much time in if I was expecting one or two to put in real minutes their sophomore year.  Do your upperclassmen still have room to grow?  If they do, and you think you can make a run this season or next, I would put maybe 22 minutes into both off/def, Maybe 24 into defense. 

I've been using 25 minutes in each for a while now, and I still get 4-year players who don't reach A+ by the end of their Senior years. 

I go 25/25...maximize the IQ's, because most of my players are maxing out (or extremely close to it) by the end of their senior seasons anyhow. 

Thanks for the responses everyone. My seniors don't have room to grow and are pretty pathetic anyway. Next year I only have two SRs and both are pretty bad. It's a young team that I'm starting from scratch with that has little talent. Thanks for the advice.