I'm right at 7" and 5.75" thick. My wife (5'5", about 125 lbs), thinks it's more than big enough for her, but her getting a bigger dick is not the only thing cuckolding is about. It's about fucking someone other than your husband and then playing with that fact, when she knows he loves it!
That's why we never really "get" the whole bull stud thing in this group. She's had big, and it's not always better, and doesn't add much to the whole cuckolding thing for us. Unless the guy is really pounding hard and slamming her cervix, she has a hard time telling the difference between someone like me and a "bull" an inch or two longer. She can't even imagine having ten or eleven inches in her, although I wouldn't mind watching that action from a closet...
Most of what she has seen over her 34 years has been about the same as mine and sometimes thinnner. Only one was really small, like five inches and thin, but she said he was still good in bed. Only a couple times did she get an 8"or 9" cock and thick. The 9"er, a somewhat short Brazilian guy, was super-thick, hurt a bit, and, unfortunately, didn't know how to fuck very well. The 8"er OTOH, was more comfortable and knew what he was doing.
Well, every girl in the office fucked him, but he finally got snagged and moved on. What a shame!
I had a similar experience with a total knockout redhead who was so totally inept in bed it felt like I was fucking a sack of potatoes. So, it works both ways, I guess. My wife's advice is to stop obsessing about bull cocks (and your little cocks) and get to work licking your wives' pussies -- because that's where most men fail in bed.