I dont think you should be randomizing your bet sizing, either bet opportunistically or "standard". Fish dont tend to notice if you are betting 40% pot or 60% pot, and if its a reg and the standard flop size bet in the game is 50% just bet 50%. Or even better yet if you have enough reads on the reg -exploit him with your bet sizing- lets say the villan folds way to much to cbet, then cbet smaller- then the villan will either have to adjust or continue to get exploited.