while we're learning new skills, there is no such thing as failure.
it's just a combination of "not there yet" and "what can i learn from this episode"?
if you decide you just "flat" don't enjoy working a technique, then it's perfectly fine to scratch it off your list of things to do.
it only counts as a failure if you give up too soon. even then ... so what? who cares? life's too short to worry about it. ;-)