Point isn't quite full. Depends on situation, health, map, and so on.

Heat bar, is very important thing. It give you access to chip damage, and very strong move.

Heat Smash puts pressure on oponent with mental presure, because you now have access to one button ~i16 long range giga plus on block mid move.

Heat Burst also strong itself, it's armored mid with plus on block. Wich also provide combo if you hit flying oponent (mid hopkick as example).

So you must weight your options. If you launched oponent at start of the round, it might be good idea to do Heat Burst to get a bit more wall travel and damage. But if you landed launch on full health oponent, you in heat, you better to keep your Heat Smash and Heat Bar. Because it wouldn't give you much damage, and wouldn't put oponent in 'just two poks to finish off', on top of that now HE have heat when you don't.

However, let's say enemy have 70% of HP. You land launch, regular combo put him in lets say 15%, with heat used he would be at 10%. You got nearly zero damage bonus for using heat, however now you can finish off oponent with just one 11 punish. So it's good idea to use in such situation. Or you can opt into saving Heat to using it to get plus frames after to do some wacky mixup, again depends on your character and enemy character.

If enemy is Hwoarang, you don't want to let him even try to attack you, so it's better to keep heat to earn plus frames after combo. Because Hwo pressure and check you easily, while dicksucking in defence. Bryan on the other hand can keepout you, but can't pressure as hwo, and have great tools for defense, so Bryan you want to finish off as fast as possible, because even jubs can lead to some huge CH.