You don't need to clean every single time you go to the range, that's just unnecessary, but don't a let a gun go through thousands of rounds without some attention. Most good quality guns today will be just fine for hundreds and hundreds of rounds (assuming decent quality ammo here too). Cheap guns, with cheap "dirty" ammo, will gum up faster. It's not an exact science. If you shoot regularly, try not cleaning gun and then see how long it takes before you get a malfunction of some sort, then avoid that number!