There are way too many variables to try and say what you can get, could have gotten if only you had...(fill in the blank), or should have got (usually from some misconception on the gallery makers part) The surfer is the one to decide and we will NEVER be able to make some magical layout that works with all.
Simple answer on this too often asked question is it's the luck of the draw. Every surfer is different and if you happen to get the ones that like your layouts then you get signups. But the sponsor has to pull their weight as well. If they have icky tours then no matter HOW well you do a gal, then you won't get a signup.
Lens! We need a area to just post these sort of questions!
There will *never* be a answer to this one. Or quite a few of the other common ones.