To be honest, Planet Fitness is meant to be a gym and so it's not as good as going to a dedicated tanning salon.
One thing I noticed was that the bulbs weren't maintained very well, and I was never able to get a "deep tan" from the beds unless I went super regular, and used an expensive tanning lotion too.
Unfortunately, all the PFs near me have switched to stand-up booths, so I just don't tan their anymore.
I dropped my black membership and spent the money on a proper tanning salon instead. I guess it depends if you're using the gym and stuff a lot, may be worth sticking with it then!