#1
So I'm working on 1 minute trills with each finger combo and I decided I would fret the two fingers not in use on the string below the one that I'm working on to try and develop finger independence (stopping the fingers from moving sympathetically as I trill). Could this damage my hand at all or give me some bad habits or is it perfectly all right?

An example if I was unclear is:

e - fretting the 2nd and 4th frets of the e string with my middle and pinky fingers
b 1h3p1 - doing the 1-3 finger trill on the b string
#3
Okay thanks. Yeah I usually do each one for a minute and then take like 15 seconds to shake it out between each combo.