The thing is, I use something like 30+ new tabs every day. Half of them are temporary, so I close most of them, but the other half need to stick around for 2-3 days (sometimes longer) because they're relevant to what I'm working on.

After a project, I rarely need to refer back to them, so there's no sense bookmarking them. So I usually only need tabs for 5-10 days. So I just leave them open until the project is done, and then close everything en masse. Usually that's 50+, but sometimes around 200, depending on the project.