This refers to a strong (15-17) 1NT with hand shapes of 4-3-3-3, 4-4-3-2, or 5-3-3-2.
With "flat" hand like (s) Kxx (h) Kxx (d) KJx (c) KQxx, I would refrain from bidding 1NT, after deducting one point from my "bare" 15 for the 4-3-3-3 shape. (All the x's are 7 or lower; give me two or three tens or nines and I would probably open 1NT.) Instead, I would bid one club.
Change the hand slightly to (s) Kx (h) Kxx (d) KJxx (c) KQxx, and I'd probably bid 1 diamond since I'm 2-3 in the majors, even though my shape is technically 2-3-4-4. (But if the major and minor suits were switched, so I have two high card majors, I'd bid 1NT and hope to hear 2c (Stayman) or a transfer bid.)
With a 5-4-2-2 "semibalanced" hand, I wouldn't bid 1NT with 15-16, but might do so with 17-18, deducting a point or so for two doubletons.
Would most experts refrain from bidding 1NT with 15 high card points in the above situations, or similar ones that I haven't mentioned?