For the sake of debate, I’m going to play devil’s advocate and make a case for extreme length.
I’ve continued to browse around the fisting forums, and have now found a second case of increasing vaginal depth, this time from about 7 to 9 (the other one was from 6 to 8). This suggests that some women will adjust to extreme lengths over time.
I also found a couple threads where women measure the depth of their vagina to the vulva and combined the data set.
6.25”
6.5”
6.5”
6.5”
7”
7 “
7.25
7.5”
7.5”
7.5”
8”
8”
8.25”
10.5”
Which is an average depth of about 7.5” NBP for willing respondents among extreme inserters.
It’s possible some of these women could have gone deeper with narrower toys (they are generally inserting 7” - 9”+ circumferences) and one of the stats is from a woman who got 8.25” deep with a 6.75” girth toy while she could only get 7.5” with a 8.5” girth toy. So maybe their average stats could be ~0.75” deeper with more common penis girths in the 5-7” EG range.
Women who are into stretching, fisting, and insertions - tend to do max depth insertions - reaching to the back walls of the pussy (the fornices). It’s possible that after years of this style of play, these women have stretched their depths without even realizing it.
Anatomically, there is every reason to believe a vagina will stretch in depth over time, provided that it is not limited by the rear bones of the pelvis (the spine). Stretching via the anterior fornix is less likely to be limited by the spine.
The theory that vaginal depth is primarily spine limited suggests a depth range of 5-7 inches over a large sample (a sample of 203 mothers diagonal conjugates were measured at 10-16 cm). It’s rather obvious that the spine is not limiting depth in many cases (anyone who is deeper than 7” is very likely not spine-limited)
Women who enjoy this type of play generally do full insertions. That is to say, if they’re 7 inches deep, they insert their very wide toy the full 7 inches. They want to be full. That is a case to be at least long enough to bottom out. For the moment I’ll set aside the downsides to bottoming out.
The most sensitive part of the penis is the upper shaft, so even when we do bottom out, we are still getting all the stimulation we need on the upper shaft.
Cervix limitations and fornices - many women do not like their cervix bumped and those women may be underestimating their depth. Even among fisters and inserters, some of them take time to discover their fornices. For inexperienced women, it’s possible that they believe their vaginal depth is about 1-2” less than it really is. They experience pain or resistance at the cervix, whereas a skilled male lover with a long tool can slide past the cervix. This would in part explain why many female sources around the internet have quoted their “ideal lengths” in the 4.5 - 6.5” range when the fisting women are reporting their vaginal depths around 7.5”.
A penis that is “too long” could be thought of as “long enough” to completely fill her up; to stimulate the fornices and cervix in a way that is pleasurable (sliding into the pockets) rather than painful (bumping into the cervix). Both partners still get their orgasms, and hers may be even better and fuller.
Among women who are not spine-limited in depth, there would be a “stretchy zone” of depth, where the penis is in a fornix, touching the end of the vaginal walls, but there are a couple inches of give, the stretched length. Bottoming out would not be a hard limit, but rather a range of increasing resistance.pleasurable to both. A best of both worlds scenario in which she is completely full, and you can still grind.
So there you have it, a case for going to 8 NBP or so. Or if you can truly tap into the mindset of “bottoming out is a good thing” then why not 9 NBP?
Remember this was a devil’s advocate post - I’m not sure I even convinced myself. There are plenty of reasons to avoid becoming too long to bottom out, and plenty of female sources around the net indicating an average ideal length of 5-7 NBP.