Fortunately, one can raise the pressure in a mat by squeezing it. For really small or extra smooth waves, I let out air until I can fold my mat to look like the number 7. Even less air often frees up the mat in little bowly waves. You can always compress the outer front corner with your fist to hang in through steep sections and make hard turns.
I find that the 90 degree L-bend is good for 3-4 footers. Then, as the power and steepness of the surf increases, I tend to add liberal amounts of air. For scary suckouts, I'll inflate my mat as hard as I think it will go without popping. A soft mat gets long glides and a hard mat will resist slides...
