Excellent question. I look at a combination of these questions:

(1) Do I really like this premise still? Or am I kind of sick of it?

(2) Did I vet this premise with my reading group, an online group, friends, etc.?

(3) Is this my first attempt at this piece? (Meaning I haven't yet put it aside for a while and looked with fresh eyes.)

I think answering those 3 helps.

Strong Yes to 1 is a good reason to keep going, or just pause for a while.

Yes to 2 helps but is not conclusive. (Not every beloved premise needs to be written, but you should try).

Yes to 3 is good reason to press pause (rather than give up).