How do people with no gap yr get 3~4k+ hours of research??

I'm going to be starting working a inorg lab from this summer as part of the starting members (cuz my prof is new this yr), but even if I assume 400 hours/summer for 2 summers and 800 hours for 2 academic years, that's still only 1600 hours. I've seen that applicants who are research focused will have 3000~4000 hours and multiple publications, so I was wondering how that's possible.
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Pre-Medical (MD) Source Type: forums