In my experience, there is no good solution to this problem- when feature X comes along and it is decided that the ongoing work on A,B,C need to be paused becau

In my experience, there is no good solution to this problem- when feature X comes along and it is decided that the ongoing work on A,B,C need to be paused because X is that important, there really is no way to quickly context switch back to A,B,C after X is finished. The best thing you can do, in my experience, is make sure that the devs are fully bought in on why X is so much more important than A,B,C. Ideally, you want to present it to them as 'X enables us to get this contract/solve an uptime issue/whatever' and then let them decide, as a group, that maybe we continue on B while the two working on A and C instead focus on X.