You don't really know that much about vagina, friend.
Vaginal depth/width varies just like penis size, a woman being "loose" has nothing to do with the amount of dikk she's taking, it has to do with how aroused she is. The vagina relaxes when a woman is properly excited and will naturally be loose upon entry, if you're doing what you're supposed to the muscles will spasm and tighten up around you once you're in it. If you don't know how to pre-game...or your dikk game is wack, you may find yourself wading around in the wide open waters of lake minnetonka wondering why there's no kick back.
Multiple child birth is the only thing that permanently alters the size of a woman's vagina. Even then it's not that dramatic of a change, and kegels can always strengthen the pelvic floor. The myth that your p*ssy somehow falls apart every time it encounters a mighty penis is really just men ego tripping and pretending like they know more about a woman's body than they do.
The only time a p*ssy is extra tight (unless you just have exceptionally large penis) is when they aren't exactly in the mood, or uncomfortable. With your vast knowledge I can see how you might think a resistant p*ssy would be the norm, but it's not.
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