Newbie to tubeless last year, digging out the racey wheels which have been in the cellar over the winter. I can still hear a little bit of sealant sloshing around but certainly less than before. Do I need to add some or should it still be OK? Is there a point where you need to wash out the gunk and start again? Thanks.
If you can hear it sloshing then it should be ok. If you can't hear it then it needs topping up. Also, if you get a thorn through the tyre, the sealant forms clumps on the inside which break off and start to rattle, therefore if you hear a rattling then it's time to remove the thorns and patch the tyre on the inside.
Stans?
It depends on a lot of things. Some tires are more porous than others. Hot, dry weather dries it out faster. My bike spends a lot of time in the covered bed of my truck and it gets pretty hot in the summer. I typically add about 1 oz of sealant every month or so in the summer, less often during cooler weather.
Cool cheers.