Hello mimir, welcome to the forum!
If properly treated with electrolysis, a hair follicle requires 1 time to die. Not 10, 7, or 3 - ONE.
The “3 clearances” strategy refers to an area, not individual hair follicles. Let’s say you haven’t removed hair in an area of your body for several months (4+ months). All the visible hair you see looking at that body part is not all the hair you grow. Some hairs are still under the skin, or have been shed and will start growing again. Same thing applies to an area of the body that has been waxed or shaven recently - except that the amount of visible hairs will “trickle in” and be treated in more sessions instead of cleared en masse then maintained.
Electrolysis can only treat those visible hairs above the skin referenced above. That’s why you have to go again for treatments in an area even though it takes 1 zap from electrolysis for a hair follicle to die.
With “3 clearances”, all the hair in a given area will be removed, then again in 4+ months, then again in 4+ months. By the 3rd clearance, there is a very small or no percentage of hair left.
If you have an incompetent electrologist who plucks the hair instead of properly treating it (it should slide out without pain), you may be having treatments indefinitely.
Sometimes electrologists say “the hair takes x amount of times to die” because that sounds simpler for the consumer, instead of going on about hair growth cycles. What she maybe trying to say is “you’ll have to come in x amount times before an area of your body is hair-free permanently”. Or maybe what she said to you is what she actually believes. I don’t know. But it is not the truth.