Electrolysis is permanent hair removal, a fine her may take one treatment whereas a thicker hair may need more treatments. If a hair is treated it needs to be retreated 6 weeks later. Reason being is because it will be a new hair and new hairs have juicy moist follicles.
The more moisture the better it will work because the moisture is turned into sodium hydroxide or with heat method the moisture is cooked.
You can turn the current up and down according to the clients pain threshold. So a hair on a higher current might take 2 treatments or 3-4 on a lower current. Despite the low current it will still ultimately die.