That is ever so true.Some people start to get really good at 50 dives.
Some people never get it.
There is no number that works.
My introduction to scuba came 36 years ago at a resort in Hawai'i. An instructor did a demo and class in the resort pool for anyone interested. I joined in, and he did what was essentially the beginning of a discover scuba class. He demonstrated a basic skill like clearing the mask. I would do it, and while the other people were struggling to do it, I would swim around until it was time for the next skill. (That was a standards violation, BTW.) I actually got in a pretty decent scuba experience while the other people never got off their knees. I loved it, and I signed up for the open ocean experience the next day. Others had signed up for that same experience, but they canceled when they realized it was Easter sunday. I therefore did the dive with the instructor and his girlfriend, and we had a full length dive with a max depth of about 75 feet. (Another standards violation.) I felt totally comfortable and in control. I would have gotten certified on that trip except that I separated my shoulder that afternoon trying to body surf on a beach with bad shorebreak conditions.
In contrast, someone I know took OW in New Zealand, and by his own description he was pretty much hopeless. He struggled with every skill, and he took AOW right away because he felt he needed more instruction. He said he was a mess for probably his first 100 dives, but he kept at it. When he told me that, he was the Course Director in charge of instruction in the shop where I was working.