I love to make my own galleries for promotion. But I admit its much more easier for a program owner to make FHGs and spread 'em all over than making content zips or give accesses to the affiliates... Plus I prefer to make my own banners and I need the site logos in PSD format for these. Half of the sponsors don't give this out.
Best and easiest way is when a sponsor puts these PSDs (for example JaymanCash) into the Ad Tools section and they give member area accesses to grab unq promo content on request (for Example DogFart).
Unique galleries always work better. But the number of webmasters who make these (especially good ones) are decreasing every single day.