The temperature, humidity, also the amount of fluid you may loose from punctures and poorly sealed tires are probably the most significant variables. The kind of tire may make a minor difference...the sealant slowly seeps thru the sidewalls of some tires. But I have never noticed a big difference between tires in terms of how long the sealant lasts. I cant imagine the mileage would make any difference other than its relationship with what kind of environment you are exposing your bike to while riding it. All the brands seem to last about the same length of time as far as I can tell, but to be honest, I haven't monitored this very carefully.
Maintaining tubeless tires doesn't require much thought or effort. For me, one application of sealant lasts months. I always make sure I have some sealant in stock so its there if I need it. I usually just add more sealant thru the valve stem when I can no longer hear it sloshing around in the tire when I give the wheel a spin in a quiet room. Perhaps once a year I will pop the bead and look inside the tire and clean out any solid latex boogers that may accumulate. That about all there is to it.
Last edited by mihlbach; 05-06-21 at 07:04 PM.