I can change a tyre faster than ive seen most people change a tube. Release one side of the tyre from the rim and scoop most of the sealant out with the red scoop that comes with stans sealant, or other round scoopy type object. This takes literally 10-20 seconds. Wipe what you cant out (which wont be much) with some paper towels. I’ve never bothered with scraping the old crap out, cant see the point and ive never died, and ive never had a tyre fail to seal because of this.
Re-use sealant in new tyre and add new sealant if required. easy.
edit: im not a serial tyre swapper- I generally stick with the same unless it gets very muddy which then stays on until it dosent get muddy. But if I was I’d stick with tubeless regardless.