How high is high buy-ins tournaments?
In general, just as in cash games, it is best to bet more for value with made
hands and
bluff less on lower levels/stakes. But that can change if you identify some nitty players that you can steal a lot o pots off.
The higher you play - the more balanced you should be against the population. And at the lower levels you can often identify how you can change from a balanced approach to an exploitative one quicker and against which players. As stated that is often more value heavy betting, but not always.