The average value of a move doesn't help much as a guideline. For example when I play a slow, solid move, I know for a fact that later on in the game the stone that made no territory whatsoever is going to help me make lots of territory later.
Calculating the average value of a move as the game progresses leaves you blind to what's going on on the board. Stones have function, groups have strength. You're making plans and so is your opponent. That's what matters.
At the end of a close game, each stone you played will have returned a value of around 0.5 points anyway. There's enough to worry about without trying to find out whether or not you've met quota every move. If you really are worried, do what the pros do: count relative territory every chance you get.
