All I can say is that if trying to "look" puts your hands, wrist, arms, shoulders and back in a position that detracts from your playing comfort... it can REALLY cause physical damage... I have back problems (and also wear contact lens that don't focus as well at very close range) so I play in a relaxed balanced, untwisted
position, with the face of the guitar aimed at the imaginary audience instead of at the ceiling) I can't actually see my LH at all... I have little blobs of office correction fluid (white-out) painted on the side of the neck that I can see in my peripheral vision while still looking at the music... With practice, I learned the fretboard by touch only (many different sizes in fact, from 433mm-670mm) I occasionally glance at the dots to gage a long jump, but otherwise never look.
I visualize a mental map of the frets and nodes where the strings cross them. I do sometimes wonder if not visualizing my fingers may have deprived me of a possible "memory aid"... but I will say that when I started playing the lute with 25 strings... I knew that looking down at all of those strings caused mild PANIC and total visual disorientation! (double vision x25)
Learning by touch was much easier! The only time I ever get lost reading is when I try to look (and then find my place again)....
Maybe in another ten years I have the nerve to try playing from memory... but for now I'll stick to playing and reading without looking at my hands... at least I'm sitting
comfortably, and don't get lost, which have a far bigger impact on my playing!