Hygiene on the T

I rode the Red Line after I finished busking at Davis, and next to me was a young woman who filed her nails all the way from Porter to Central.

Granted, I keep my nails short to the quick most of the time, so can someone tell me, how long does it take to file one's nails to satisfaction, and is there any reason it needs to be done in public? I mean, I can understand having a ragged edge one needs to deal with immediately, but I'm pretty sure that should only take a few seconds. I didn't know until then that the sound of someone else using an emery board grates on my nerves like it does.

Now don't get me wrong, I generally wish more people would practice hygiene before getting on the T, such as showering and wearing deodorant, and then controlling certain bodily functions when in a small space with dozens of other people and little, if any, fresh air. But I think nail filing can wait.