I've had good results with doing similar. My spelling and grammar have always been a challenge and, even when I put the effort into checking something, I get blind to things like repeating words or phases when I try to restructure sentences.

I sometimes also ask for justification of why I should change something which I hope, longer term, rubs off and helps me improve on my own.

I have definitely seen Grammarly make suggestions that are actually wrong, but I think it's generally pretty ok, and it does seem to make fewer mistakes than I normally do.

Sometimes I use incorrect grammar on purpose for rhetorical purposes, but usually I want the obvious mistakes to be cleaned up. I don't listen to it for any of its stylistic changes.