For my wife, the most men she did at one time was a gangbang I organized for her birthday one year. We had 22 men show up that year which was much more than the usual 7 that normally show up most years for her annual birthday gangbang. That year, 17 of the men were able to get hard and perform. She had her mouth, pussy, and ass filled for several hours. Of the 5 guys who could not get or keep it up, several got sucked while trying to get it up.
That was too many for her and while initially excited she said afterward, she got sore and numb so after roughly 7 or 8 it was not pleasurable but she kept going.