I clean my lint trap every load, always have, and I can't imagine not doing that, because it's pretty full after just one load.He also said to clean your lint filter every time you run your dryer and if you use dryer sheets to scrub it every so often because a film will build up and clog the mesh holes.
For easy cleaning, I either soak it in hot water or just toss it in the dishwasher. It makes a big difference in the ability of the dryer to get clothes dry.