In Dalio's Principles, he talks about knowing what's "over the bar" on work. Meaning, what's good enough quality given the type of work you're doing.
Dalio makes the point that you should get all work over the bar before turning to polish other work up to excellent. Excellent takes a lot longer, and if you have a half-complete machine that's half excellently made but half incomplete, you have nothing.
It's a simple point, but doesn't come naturally to most of us. You have to get all work over the bar -- meaning, good enough quality given your requirements -- before polishing anything in particular to perfection.
On rare occasions this doesn't apply, but usually it does. Get everything functionally complete before obsessing over finer points.