Make sure to constantly be reviewing setup guides while doing it. If you get stuck in a pattern of improper setup then it will seem like the setup just isn't working for no reason at all.
From what I understand the most important thing is setting up skew properly. If the timing was hard enough that you couldn't get it in a few tries, it wouldn't be consistent enough for the speedrun. So just keep at it.
The only useful purpose of shield clipping is to cheat your way through the trial of the sword, and doing the challenge is the whole point of it so unless you're doing the speedrun there's no point spending the time learning it
If you are doing the speedrun you should join a discord for that...