This might be a noob question and I think I know the answer but, when it says:
In that case, could you use R after you miss the first try to tech with L?In order to tech, you have to get a precise timing and not resort to button mashing.
Whenever you press L, it enables you to tech in the 20 following frames, but it also prevents you completely from using L to tech again in the following 40 frames.