Just for one anecdote, three years ago my then-dentist (who was a part of a franchise practice and probably under pressure to bill) told me that I had 12 (!!) cavities across all quadrants of my mouth that needed to be filled immediately.
I went to another dentist in the area, they took some x-rays themselves, and told me that there was nothing that needed immediate work - maybe one pre-cavity that would eventually turn in to something but certainly not worth doing anything with now.
Three years later (and sticking with that new dentist) I still haven't needed to have anything done (and certainly don't have any pain in my mouth anywhere either).
I went to another dentist in the area, they took some x-rays themselves, and told me that there was nothing that needed immediate work - maybe one pre-cavity that would eventually turn in to something but certainly not worth doing anything with now.
Three years later (and sticking with that new dentist) I still haven't needed to have anything done (and certainly don't have any pain in my mouth anywhere either).