In the past, condoms have been made as one-size for everyone. It's been found that condoms often fail to work properly because they're not the right size. If a condom is too tight, it can break, and if it's too loose, it can slip off or just as easily break because of the extra friction. Width is more important than length.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/which-types-of-condoms-are-best-for-preventing-pregnancy