You should never threaten things for the sake of threatening.
Before kicking opponents pieces around, consider
- Where will the piece go? Can it go to a better square than it is on now? (If so, don't kick. Let him waste the tempo to improve his piece -- unless your gain from the kick is much greater than his gain..).
- Do you gain anything from the kick? Improving one of your pieces or getting a pawn advance going are valid reasons.
- Does the kick allow tactics (i.e. kicking a defender of a pawn away, so the pawn hangs)
- Are you short on time in a blitz game? Then a threat can be a way to pass the ball your opponent so you can look for a better move while he thinks.
Essentially, explain to yourself exactly what you gain by the threat -- and if you cannot see any gain, maybe look for alternative moves.
I imagine you would attack a piece even though it could run away because your thinking to yourself that if your piece, was on that square, maybe your overall position on the board would be better. I'm taking development into consideration too, advancing your pawns forward, putting pressure on such a square to gain more of a foot hold on it, and because you want the piece your attacking to retreat to a particular square for whatever reason.
So my question is, is there any more to it? Did I just sum up pretty much every common reason why someone would attack a piece even though it could retreat? I thought this was a good question to ask. Nobody wants to "miss" something you know lol. My rating isn't so good and I haven't even played many games so if your really good in chess, or you think I may haved missed something regardless of your rating, please respond. I'd really appreciate it.
Uh, one more thing, if your answer is going to be to either win a piece or get someone into checkmate, I've thought of that haha
Ok. Cheers :)