If you use sprints, how long are they? I’ve typically seen two weeks.
Two weeks equals 10 working days.
If you need 10 working days to focus on something to get it done, you might have oversized work increments.
I offer you an experiment over your next sprint: plot the number of work items completed each day.
If you’re picking work items of reasonable size, we’d expect to see a uniform distribution.
What does your distribution look like?