inside shooting is fairly ineffective if jump shot is low.
Is this really true? This is an honest question and not a challenge. I've understood that the two are separate. JS means mid-range to long range jumpshots. IS means low post to to inside the paint shots (that includes jump shot inside the paint).
In a strict sense, I think you are correct.
On the other hand... The engine is always trying to find a higher quality shot. If you can take better shots from different areas of the court, it is only going to make your player's inside shooting better.
For example, play really close attention to some recent look inside games. You will notice, on balance, that a fairly high proportion of the shots are short range jump shots. So of course, if you improve your C's jump shooting, you will also improve his inside shooting.
Then again, the same could be said of a PG for inside shot. But most people will tell you that inside shooting on a PG is not necessary. ;-) Much also depends on the skill level of the other 4 players on the court.
Run of the Mill Canadian Manager