My butternuts sometimes do that too. In which case I go with the fingernail test - if the rind is hard to pierce with a fingernail you're probably good.

Ah, thank you. they easily pass that test.

Yes, most times all are gone but after a month I say harvest. Assuming the rest has changed color. I agree with the hard rind comment.

FWIW, I had a couple of volunteer butternut vines destroyed by caterpillars before the fruit was fully ripe - and the rinds had been damaged by the caterpillars too, so I harvested them and let them sit on the counter. They did not pass the fingernail test, and I didn't have high hopes, but over several weeks, they continued to ripen and the wounds - some of which were rather deep - all scarred over. When I finally cooked them, they were wonderfully sweet too.

I'm willing to wait a few weeks and see if the green streaks in the harvested squash disappear on their own.