Keep in mind of the minimum call time. A fan can always go longer (and spend more) so jacking up the price per minute and being greedy isn't the best strategy.
Nara Ford for example charges $100/minute for a video call with a 10 minute minimum. Unless someone rich has cash to burn who's paying at least 1k?
Kenzie's $15/minute (3 minutes minimum = $45) is appealing enough that most probably double the time (6 minutes) and spend $90
As for personal video customs, her rates are lower than OnlyFans but cost depends what you ask for, length and if she wants to do it