Even in/out of high it'll grind/bind (especially coming out) if the wheels aren't turning the same speed (or someone forgot to lock their hubs). The dodge recommendation was to slowly creep forward while shifting, nothing at speed with the 205. I know my np205 doesn't like shifting at anything over about 5mph into high and only goes into low at a standstill. My 208 and 231 on the other hand, says ok to shift in/out at anything under 35mph.
Wheels not turning at the same speed is indeed a big factor. But, there are cases when turning actually makes it easier to disengage 4WD.
Also, wheel speed is determined by static loaded radius of the tires, which is dependent on inflation pressure and load. For example, with 60 psi in all four tires on an M1008, but no load in the bed, the rear wheels will try to go faster than the fronts, making it harder to engage/disengage 4WD while going in a straight line. And harder yet if turning.
Again, I have never driven a part-time 'case that couldn't be shifted at speed (2WD/4WD), and the majority of them could be shifted between high and low range wile moving (at lower speeds, of course) without any drama or grinding. The one exception was a '91 Chevy Crew Cab (4L80E/NP205), but I figured that it was my inexperience that made itself heard as I really only used 2WD Low (hubs unlocked) on that one, and not very often.
From the opposite end of the spectrum, before installing lower gears in my Jeep's transfer case, shifting through all the gears in the correct sequence for getting progressively higher ratios (including engaging the Warn overdrive) meant starting in low range, going to high range, back into low range, and then into high again. That's using three levers, frequently shifting two at once, and at one point shifting all three at once. Yeah, it took a bit of practice to get it right, but it's doable.
