I've not really had the opportunity to test this as my ex just didn't want me near her cervix and at the time I knew nothing about the A-spot, P-spot or really much about the cervix other than to not go too deep with her. It appears to be all about positioning and making sure the woman communicates well with you in terms of what feels good, what hurts, etc. In other words, you have to be careful to have the right angle and the right curve to make sure you're not thrusting into her cervix, unless she's into that kind of thing (and that may only be sometimes). Apparently, some women like their cervix getting hit sometimes, and sometimes not.
It seems that you really shouldn't be going around the cervix early on before she's very well aroused. As has already been discussed the vagina should (has?) to be properly tented before taking anything near her cervix, for probably most women, because it's painful on contact. When the vagina is properly tented, i.e., they're fully aroused, the vagina lengthens just like the penis, and uterus/cervix withdraws to make room for penetration both before and after her cervix. See
http://www.penissizedebate.com/images/doc/vagina_tented.jpg.
So, here's my question for women that don't like longer dicks. Are they getting properly aroused first? Is their vagina properly tented before trying to go that deep with them? I'm curious that maybe some women have a vagina that doesn't tent as well as others, and there's simply not room for a longer penis? And maybe that's why these women like an average sized guy. Or maybe their initial experience with a longer penis didn't go well, or they had a guy that didn't know what he was doing and didn't get them properly aroused/tented before trying to insert his dick too far, which caused pain, and so now these women recoil and tense up when they are with a guy with a bigger dick, which only compounds the problem? Others just may have a more shallow vagina. Apparently the depth can vary widely from woman to woman. Just curious about why the A-spot and P-spot seem to work for some but not others.