Originally Posted by SystemicAnomaly
It might be optimal in many cases but is not absolutely necessary. I have seen elite players hit the IO shot on the inside as well as the outside of the ball. If the OP is having difficulty keeping the ball out of the alley, I would suggest going primarily for the outside of the ball for a while. Here is Gary Sakuma (hi10spro) hitting IO forehands. While he hits some of them on the inside of the ball, many are on the outside (particularly in the 1st part of this video):
I hear ya. Good point.
Yonex VCore 100s - SW 351 6pts HL
Tour Bite / Luxilon 4G 16 @ 51lbs