Well just like anything with human bodies those at the extremes are rare. The absolute thickest of dicks is as uncommon as the longest but, in my experience, you see a lot more 'thicker' cocks than you see 'longer'.
It isn't unusual to see a decent number of 5-6" long dicks that would make your jaw ache from the girth. Or provide you with a satisfying stretch elsewhere. From the point of view of sexual pleasure this is what's important as it's the stretch that lets you know you're really taking something. Length is more a case of do I go deep enough inside to comfortably take it, if not it hurts.
For women this depth is truly finite as bashing into the cervix, once her vagina reaches its limits, isn't pleasant, isn't supposed to be that pleasant for the man either and there's absolutely no way to go through the cervix.
For men the longer dicks encounter the junction between the rectum and the sigmoid colon. This is the delightfully named 'second hole' and, just like the cervix, feels pretty awful if you bash into it. Unlike a cervix though the second hole will relax but you need to coax it open. Once open you can go in much deeper. This is why there are so many size queens in the gay community wanting longer and longer dicks to sit on. Once that second hole is open you are pretty much bottomless when it comes to any human sized penis.
Navigating the second hole in a comfortable, reliable, fashion is not easy though and lots of men do not want a dick that's long enough to poke against it. Much like some women will just look at a very long dick and go nope!
Girth, on the other hand, is usually cheered for because that stretch always feels good and presses against the good spots without the guy even needing to try with the angles.
The thing about condom sizes is that the companies making them need to provide a product that is absolutely not going to fall off. To ensure this doesn't happen the standard size condom needs to be made tight enough so that it's snug on the thinner side of dicks. This means that it's likely to feel somewhat tight on the guy with an average thickness. So long as it isn't painful then it's not too tight. For me condoms that are too tight tend to be felt during orgasm as the urethra is pinched off. When I ejaculate the condom acts as a tourniquet and it hurts as the semen is forced out. Then I usually find a red band around the base of my dick where the condom was gripping the skin. It's not the end of the world but it's not exactly great either.
Even if you're only 5" long. If you need a large/extra large condom to fit around your girth then that's what you have to do.
