In my experience, if I leave a set of tubeless wheels to sit for months on end without being moved they will usually lose all air, and the sealant will collect at the low point of the tire and eventually start to dry up into a big glob. If this happens, I prefer to remove the glob, which means I'm pulling off the tire, cleaning up the rim and old sealant, and installing fresh.
I am able to avoid the glob by just moving the wheels around/spinning them every few weeks and keeping them aired up. If I were feeling proactive and knew that I'd be hanging up the bike (or wheels) for a few months without touching them, I'd probably pull the existing sealant out with a syringe first. I swap tires on my tubeless setups frequently enough that pulling a tire off to clean out dried sealant isn't really a big deal.