The correct bluff frequency should not be very high. You can read about the correct bluff frequency in Sklansky's book "Theory of Poker". There is a chapter with a corresponding title.
In tournaments, it's generally better to bluff less. At the push-fold stage, you don't need to bluff at all (when the stack is < 20bb).
If you played tight for a long time in a certain tournament and showed only strong cards at showdown, then you have image of a tight player and can allow you to bluff sometimes more often but not at the same time against several players. But if you are reseating to a table with other players, you will have to build your image again.