I have some exercises for finger independence (for left hand); however, I cannot even start to do some of them correctly.
The most difficult exercise is:
Start with a hand and all fingers in a straight line; then, flex the fingers repeatedly, each time only one finger, so that the others don't move.
After flexing each finger, straighten it back before flexing the next one.
I cannot flex the 2nd and 4th finger correctly - other fingers move significantly when I try to do it.
So, my question is: should I try to do this exercise anyway, or should I leave it for now, and try it in future, when I master other (presumably easier) ones?