Not sure about Xmas stashes in other worlds as most of my exp with scouting stashes for wheel spins comes from Wolfie World. I am not sure that the % chance of getting a wheel spin changes with time independent of other factors such as number of stashes scouted. That is way harder to prove without an awful lot of work. Since I send out 40 scouts at lightning speed on Wolfie World it would be next to impossible to monitor the success rates of all scouts. What I do do tho is record the results of every single spin in a spreadsheet which has some nice calculations going on in it all the time. Each 3 hour session is kept in a separate worksheet for future calculations. I see some very wierd trends in most of the sessions and some incredibly unbelievable combinations of spins. I started recording them because I began to suspect that the spins were not exactly coming from a standard random algorithm.