Repeated, hair growth happens on different cycles and not all will be active at the same time. Need a short root for the Lazer energy to kill the root and sometimes one hit does not kill the base and needs to be hit again. https://milanlaser.com/inclusive-clientele/trans

https://www.reddit.com/r/MtF/comments/15zbz45/does_anyone_have_experience_with_milans_unlimited/

You need to get the whole area done repeatedly, the follicles only die if they get zapped during a certain phase in their growth cycle. Typically laser sessions are spaced about a month apart to allow time for previously killed hairs to fall out and the remaining ones to make some progress in their cycle, you can expect to lose like 10-20% of the remaining hairs with each session.