If a person who's high risk for melanoma gets skin checks every 3 months, would they always be able to catch a melanoma early?

Melanoma : Frequent skin exams performed by a dermatologist , in addition to monthly self exams would greatly increase the chances that a melanoma is detected early.

Usually but...: There are no 100% guarantees, however the more vigilant you are the more likely it is that you will catch the problem earlier. Unfortunately sometimes melanoma can exist undetected until it has already advanced.