I did peri massage with no1 religiously from 34weeks and didn't have any tears or grazes. With my second I started half heartedly at 35weeks and had DD at 36weeks so it didn't have time to work well I guess. I had multiple thick grazes to the urethra, clitoris and labia minora. I guess peri massage doesn't exactly massage the urethra lol so I guess it wouldn't have helped. I definately believe it helped with my first. I was young (17) and hadn't been sexually active long (not to say that has anything to do with it) and was much smaller down below and didn't have any tears with no1 but did with no2. They were also the same size.
I re-read what I wrote before and I didn't intend to scare anyone. Personally as a midwife I can't say people complain about their vagina's post birth except they might be tender and request ice or panadol. Mine stung when peeing but TBH DH has made me feel worse then my births did in that department.