I think asking punters, whose experience of anal may mainly be with service providers who offer the service, will probably be of limited value.
On the occasions when I have had anal with SPs they have managed it without any drama - but plenty of lube - a couple asked me to go slowly at first but all were able to take a good pounding.
In civvy life I had anal with a few girls but never, as far as I know, popped anyone's cherry. One long term girlfriend enjoyed it as much as normal sex but was very tight and did bleed slightly on one occasion. Again when warmed up I was able to thrust away with abandon.
One thing I have noticed is that there was a noticeable difference in initial tightness between some of the girls. One, who was quite conservative in the bedroom, took my cock easily in the back passage without any evidence of pain.
So, to your original question, who knows? And unless a woman is getting very regular back door action I think her bum would not somehow stretch after the first time.
I would quit worrying and enjoy having a partner that is adventurous in bed.