any loose objects must be put in a locker before some rides.
i stay onsite for a number of days so not all my park times are for rides.
on the days i take the mug with me, i never hit a ride.
i enjoy using the refilable mug those days wandering in the parks, visiting with friends, taking pictures and of course my time with Mystic Fountain.......
The one caveat that other forums have mentioned go back and forth are the Coke Freestyle Mugs. Last I heard, those were only eligible for a discount on an extra day on the Freestyle machine and not valid for the $.99 refills. I don't have a fancy mug, but I still use my red mug from 2006. It has a handle though so I can carabiner it to my belt when It's empty.