Flush Outs (the Cautious way)

[Rallenkov]

In every book and in every Outs Chart I see people count 9 Outs on a flush draw.
My Question is, would it not be better to discount 1 Out for every 2 Players.

Theoreticaly every 4th card should be of the same suit as our hole cards (a little less since we already see 4 cards of that suite but since this is the cautious way we go with every 4 for this example).