So we have a very diligent PO who does a good job of prioritising the User Stories in the backlog when it comes to planning. Much of the work is highly specialised though, and - as well as being Scrum Master - I'm a generalist developer and my team has some quite greenhorn juniors. Hence, what happens at planning is that our sprint gets filled to capacity, but then there are people (often me!) left with low allocation because there aren't really that many stories appropriate to their skillsets and levels.
My instinct (especially in this time of remote working when communications are harder and motivation is not always guaranteed) is when the sprint is full, to skip stories in the backlog to find them things they can do. This has annoyed the PO as he wants things done in priority order.
So there's conflict here - stories ordered solely by business goals might not get done, or might get poorly done if allocated to the wrong person. Even skilled devs working in a relatively new area will make mistakes. And switching people in and out of epics seems like a bad idea in some ways. My pragmatic solution - keep priority order till the sprint is full, then skip, hasn't been accepted by the PO and I am left a bit confused as to how to move forward.