Notice as soon as your hand hits the end, a glowing ball of energy the size of Sheik's head sparks & then erupts. The time from spark->erupt is same as @
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mentioned about the moment Sheik's legs swing down & being to hang vertically. That moment & the end of that little erupting ball of light can indicate your ledge grab animation is over, & free to drop again. As far as that step goes (hardest part imo), time your ledge-drop to those 2 things.
There's no "even" rhythm, so those extra frames before u can let go of ledge again might be throwing you off, they still do for me sometimes.
Practice @ the Hyrule "Temple" in middle of stage, so you don't have to die every time. Fox's ship stage moves slightly so would've be as optimal a change. Lol me & my friends call that stage the bounce house, cuz u stay alive longer in a FFA from all the wall techs.
1 more tip since I don't get to post often; forget about being able to do it 20x in a row. Use it only if enemy is playing real close to the edge. If you're using it to bait them closer, mix in a few ledge-drop->fast fall->double-jump-> 1/2 of up-B to regrab ledge. It's almost invincible as well, & can surely bait them in for when u shino-stall right after. But even more important for saving ur stocks, might be your ability to ledge-dash (letting go of ledge asap->jump->waveland on to stage) RIGHT after ledge-grab animation is over.
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