From what I've observed top players flag mines very minimally, only so that they can strategically chord in certain situations. Lists of record scores typically make a distinction between flagging mines vs. not doing so. I never flag mines, but I'm also not that good compared to the best of the best.
For reference, the best of the best is Kamil Murański. There is only a 0.4 second difference between his NF (No Flag) time and his normal expert world record:
For reference, the best of the best is Kamil Murański. There is only a 0.4 second difference between his NF (No Flag) time and his normal expert world record:
https://www.youtube.com/watch?v=GrZCWx0fnfc (flagging)
https://www.youtube.com/watch?v=8bsLwGf-vUE (no flagging)