For current division I don't think they need more IS than they already have. If I were in Div.5, I'd much rather train DR for purpose of going to the rim instead of IS since in Div.5 managers probably don't care a lot about secondaries on their guards like ID and SB.
I have a PG that constantly improved in DR and JS as I moved up to higher leagues and he always maintained %FG above 0.400. I always played PtB or LI to maximise his potential though. Now he looks like this:
JS 13, JR 6
OD15, HA 13
DR 14, PA 12
IS 2
When I play outside tactics, I always play him at SF.
So unless you are facing really tough opponents that you will start seeing in D.III and D.II, Inside shot is really not a priority, but more a luxury; high DR will do.
For D.V, I think DR 11 on your guards will be more than enough to beat the hell out of every team you face.