Ran into this with my Corona D40, after getting used to my D25 and F65ce's "Modern Flat Oval" necks.
It always felt "stiffer" up and down the fretboard, I figured it had what I called the "Fender set-up", being from Corona, and it felt like the '80's Fender MIK flattop I'd had before.
Checked the action height: spot on Guild's specs where I like it, nut gap at first fret was fine, so it was a head-scratcher until one night while I was trying to "bond" with it, I noticed the neck had this very slight "thickening" at about the 5th fret, you wouldn't notice it normally, but it was an inconsistency in the tapering towards the heel, a slight "bump".
So I started looking at it more closely and realized it actually had a "D" profile (actually what Fender calls an "oval C", and almost what they call a full blown "U" higher up the neck.
Don't know if Fender was hand-shaping 'em in Corona like they did in Westerly but the "chunky" profile seems to be the most commonly mentioned from there, even in electrics.
After a couple of years I got used to it, after dedicating a lot of time to it in while the D25 was getting a refret, and afterwards too.
Now with 10-years older hands it's actually more comfortable for some things like scales higher up the neck, above the 7th fret, in fact....
The whole geometry of the hand varies from person to person but I think it's also related to what the relationship is between your thumb's ability to apply leverage at the back of the neck and what that forces your fingers to do on the fretboard.
So the thickness affects the thumb leverage.
I also first saw this in Fender's "Frontline"catalog from '01:
Note the importance they place of fretboard radius as well, that's another part of the equation.
And while looking up those photos even found there's demand for asymmetric profiles,
yeesh!,who'da thunk?: