Mine is both time and knowledge/experience. I too don't have time to browse the gallery much. I tend to only look at images that are either in the forum or have a link from there. I also still feel like I know only a fraction of what others know. I don't feel 'qualified' to offer suggestions or, more often, whatever I would suggest has already been said. I have a rule of thumb that if I have a critisizm, I have a suggestion also. I think something needs changing but I don't know how it should be changed so I won't say anything. More and more tho', I'm starting to feel a bit on par with some of the others so hopefully this will start changing for me.