Dalter, let me ask (to gain some experience) this then.
If you MAINLY run Press for your Defense, would you not want a 'fall back' defense for when you have a Late Lead? The other options seem to be "Run Defense with No IQ" which seems like it would be ripe to allow a Late Rally... or Practice Secondary Defense, which means slightly less talented players.
Now, my limited experience shows that many players have 'dead skills' or a few areas that practice just won't help "Hey Coach, maybe the time working on Johnny Utah's Free Throws could be used elsewhere, unless you can get something out of him". Perhaps not 20 Minutes to M2M or Zone, but 15, maybe 10? After all, you aren't looking for an A+ Effort, you just don't want an F on the Court.
I use 20 in Motiom, 20 in Zone and 130 in Player. I have a few, due to those 'dead skills' at 0. I could see, once GPA is up, trimming 5-10 minutes off of Study Hall and giving it to a Secondary Defense (Dimishing Returns says bumping a different ability over 30 may be less effective than 15 in a 2nd Defense).
Why is this logic so flawed?