Firefox

Same. It's just that my tasks tend to stretch multiple days and overlap, so there's rarely a clear cutoff.

I'm a software developer and team lead, so I'm often involved in two separate releases simultaneously, planning on one or two major features, and new development on another project, so I have tabs related to each. I try to make time every couple weeks to clear out a couple hundred tabs that have accumulated.

My workflow works for me though, and it feels real good to close hundreds of tabs knowing that one big project is finally finished.