When is the right moment for a coin flip?

A coin flip is a situation where two players are involved in a hand have an equal or nearly equal possibility of winning the had.Some players do that when only have 12 BB or less, they have a good position on others. I think a coin flip depends on the player, the kind of players who are involved in a hand and the remaining stack so, my question is:
When would be the right best moment to put all your chips in the hands of a coin?

While it is very difficult to determine if you are going to be in a coin flip situation before the cards a turned up, I think that the right times for a coin flip (being when you think you and your opponent will be very close) are:

-When you can afford it: If you have a lot of chips or you are still in a re-buy portion of a tournament then get her done; take the chance to add on to your stack. If you lose, you may get the table image of a caller and get bluffed less.

-Taking a stand: If you have been getting bullied by a smart, aggressive player, sooner or later you have to take a stand or else they will keep on hammering. You may even be surprised that the strength of their hand is less than you originally thought.
-To eliminate an opponent: In the later stages of a tournament, eliminating a player will have your ladder up into a better pay day. This is most advisable against players that you have a significant chip lead over. A coin flip with a large stack against your large stack is not the best idea, as you will be taking too large a risk when you don't have to. It is better to pick on people with less chips who will do less damage if you lose.
-When you have to with the short stack: Shoving a small pocket pair into 2-3 players behind you often results in a coin flip when they call with over cards. The pair will hold often, but the main reason you shove in these situations is to induce a fold and steal blinds.

I'm ready to coin flip when I get close to 20 BB, or if I'm deepstacked and have a chance to eliminate a player from a tournament. And on a rare occasion I have called a coin flip when I didn't believe someone had a good hand, i.e. When 3 of the same suit falls but neither player has that suit.