The value of slow-playing depends on position and the flop.
If you have, say, trips, but there are cards towards a flush or straight, you don't really want to slow-play. You want to hit it. If you hit quads or nut full, then perhaps slow-play.
Against a tight player, slow-playing will just risk a lucky draw without getting many more chips from them, and you'd be better off placing a relatively weak bet if you are looking for value and are happy with the risk.
If you're against an aggressive player, then slow-playing may work well enough.
If you're in late position, then you have more opportunity to evaluate the strength of your opponents hands. You want to bet when they have made a reasonable (but dominated) hand.
Also, against fish, you'll often get more action earlier on, when they want to stay in on the off-chance of hitting a card (not understanding their poor chances) - later on in the hand they'll be likely to have missed and less likely to pay you off, not more, so slow-playing may well not work there either.