Hi Thiamtan,
When it comes to the differences in the strategies that are required for cash games or SNGs/MTTs, I think the main thing that matters is that you need to have a good knowledge of the ICM and the dynamics of the game in tournament poker.
Playing TAG poker should be useful in all of these formats, so this shouldn't really be the main criterion. Every format has its own unique aspects, and generally speaking, none of them necessarily favors LAG over TAG play, though it might be useful to loosen up in a few selective spots. Adaptation is the key.
Also, the TAG style only really applies to preflop play, and especially in cash games, most of the money is won or lost after the flop.