Well, lets see....3 from Dixie Landings, 3 from POR, 3 from Polynesian, 2 from Boardwalk, 2 from AllStarMusic, 2 from Pop, 3 from Beach Club, 1 from Typhoon Lagoon. I use my Pop mug every day for my morning coffee. Dd used her for hot cocoa in school. The others sit on a shelf in the basement.
So.....that's probably not what you asked, is it??!!! Most of my mugs state on them that they are good for the duration of the trip they were bought and only for that particular resort.
Do people use them at different resorts? Yep. They use anything they can pour soda into.....mugs, cups, thermos's..whatever.
Have I reused a mug at WDW? No. Too much trouble to cart them back and forth. But that being said....I might bring my Pop mug back for my one night stay in Dec. I'll be eating two meals there, one of which is breakfast on my departure day. And I did just buy it in August. Does this make it 'right'? No, it doesn't. I can't be bothered worrying about the fact that others are filling up those 'big gulp' cups at the resorts. I'm there to have a good time. But, I will say.....this time at Pop, if I do reuse my mug, will be the time a CM decides to enforce the current rule!!!! I could be going to 'refillable mug' jail. But, it's just for 2 drinks.