Cooking sprays use chemical propellants like soy lecithin, which can build up a gummy residue over time and ruin the original nonstick coating for nonstick pans.
While the best way to preserve nonstick cookware is to never use cooking sprays on them, simmering two parts water and one part vinegar in your pan can help remove build-up.
Wipe the surface of your pan with a paper towel covered in oil before cooking to get the kind of even application that you want from a cooking spray without damaging your pan.
You could also buy an oil mister that mimics the same type of wide application as cooking sprays, but lets you use whichever oil you prefer, and won't ruin your nonstick pans.