Teams work on topics sequentially
A team can only truly work together if they work on the same things. We try to work on as few things in parallel as possible. The value of finishing a single thing is always greater than the value of having multiple things in progress at once (because the value of that is 0).
When planning our work, we focus on the goal and not on keeping everyone busy. Having the same number of tasks in progress as there are members in a team is an anti-pattern that is usually driven either by the fear of not having enough to do for everyone in the team or by the amount of topics that we see lying around in our backlog seeming so large that we feel the pressure to take on as many things as possible at the same time.