I work in a company where I'm allowed to leave meetings that aren't interesting to me. The problem is with "status update" or "brainstorming" meetings where I'

I work in a company where I'm allowed to leave meetings that aren't interesting to me. The problem is with "status update" or "brainstorming" meetings where I'm expected to contribute but only fleetingly, or intermittently. I know I'll be needed for about 2 minutes at some point, but it's not clear when.