Yes nicely put Brian.

To this bit Paul "is this to inform how a song "should" be performed?" I'd say yes to 'inform' but no to 'should.' The more you study how things were done in the past, the more options you have as craftsman. You don't have to use a wooden plane to make your new dulcimer, and it wouldn't sound any different if you did, but you might enjoy using one, and some might enjoy knowing that you'd done so.

I'm no musicologist or folklorist, but I do enjoy encountering that knowledge, and doing my own little bits of research, and I do know it informs my writing, my playing - and even (given that I have totally the wrong type of larynx and am not trying to do it 'right' anyway) at times my singing. But it doesn't control any of those things - because I'm also influenced by loads of other stuff which I also value equally. That's my choice, (and I get or don't get bookings accordingly)!

T