[WesleyC]

Trying to mastermind a certain sub-set of hands that do better opening 1M compared to 1NT is going to lead to all kinds of confirmation biases. Many bridge players - even strong ones - only remember the times when this kind of bid goes wrong. They fail to balance that against all the times that the auction starts 1NT - 3NT and the opponents lead directly into our 5c major!

rhm's post provides strong evidence that opening 1NT on all (14)15-17 HCP hands with a 5cM is winning bridge. It simplifies the subsequent auctions and tightens your 1S opening.

My best advice would be to follow this is an absolute rule and focus your energy on improving the OTHER parts of your bridge game instead.