I've been giving treatments for years, and can honestly say that (As far as I can remember, anyway!), I've never done any treatments on clients with long nails or with nail varnish on. There have been times, such as when i've had 2 weeks holiday etc where I have gone to get nail enhancements done, and though I don't find they get in the way of day to day activities, I simply cannot provide effective treatments!! I've tried to give my partner a massage with nails and it just doesn't work. Reflexology too is absolutaly impossible. I wouldn't dream of having nails on when treating a paying member of the public!
I guess it's what you get used to at the end of the day. I was always told at college that we had to have our nails so short you couldn't see them over the tips of your fingers when you had your palm facing you. We were also not allowed to have any nail varnish on as a colour can cover up dirt under the nails & you cannot keep them hygienically clean. Plus the fact that it might flake off on a client (which I still think is a bit silly, as I also use good professional quality varnishes when I bother to paint my own!). I've got so used to the college rules imposed on me that they're now second nature.
I think college rules give you a good, strict start in your professional life (or, they certainly did for me)...what you decide to do when you're qualified is up to you.