That's a hard question. I can only talk from our experience, but for us we knew we had to pivot (multiple times over the course of Alchemist, probably >6 pivots over ~10 months) because the stakeholders that we reached out to that fit our buyer personas did not think the product we offered was solving a 'hair on fire' need for them, they didn't have a budget for it because the problem we were solving wasn't among their top priorities. When we eventually pivoted to what we're doing now, we had customers echoing their problem and needs to us in word-for-word exactly how we were phrasing the problem internally, it was pretty surreal to hear people use our own words, that's when we knew we were on the path to PMF.
It shows that it doesn’t matter how much you grind it out since people compare that part of startup life to a grind, it wouldn’t have mattered anyways.