There’s a point when the idea at the back of your mind starts speaking loudly, loud enough to distract you from the thing you’re currently doing. At that point, you need to either write it down to explore further later, or pause what you’re doing to acknowledge its importance. This is, admittedly, anthropomorphizing something that doesn’t have a physical presence. But if you don’t, an important idea might either keep nagging at you, or go away entirely.
Neither prospect is much good to your work.