I never understood how people not close (or bookmark) tabs. When I'm heavily working i have 20-30 tabs open. But after the work is done, i'll close what I don'

I never understood how people not close (or bookmark) tabs. When I'm heavily working i have 20-30 tabs open. But after the work is done, i'll close what I don't need and bookmark the rest. Then again I also tend not to have more than 5 mails in my inbox.