Hello, in my case I don't usually go all in. But yes, there are different reasons why I go there.
1)
bluff where I can win a good pot and my opponent has a not so strong hand that can be retreated
2) When I have few chips and they bet before the flop, it's an easy way to withdraw money without playing the hand. Obviously I do it with more or less strong hands like A9s
3) when I have the best hand, and I know that my opponent can have ranks of good hands that are difficult to give up. Because it doesn't make sense to bet everything knowing that he's going to throw the cards when I can bet less and get value out of my hand