He had me do that in my solo diver class, but with some added complexity…
Drysuit, 104s, night, 50f water, no mask, tied up in cave line, not allowed to use cutting tools…
I wrestled with that for like 10min, finally got sorted, THUMBS. Upon surfacing he asked me, “So, what did you learn?”
“I’m NEVER diving solo in a drysuit at night in cold water with 104s again!!!
“Ok. You pass. That was the point.”
Since then it’s AL80s and a buddy bottle.
There obviously was a lot more to the class, but that was the final exam.
He always “let the water be the teacher”. Best teacher I ever worked with, with no offense to any of the other super high quality instructors I’ve been privileged to work with.