I have this downloaded. It currently says 35 mins for FJ, and 30 mins for Hippogriff. It has been 30mins all day for Hippogriff, whereas in the past week IN THE PARKS MYSELF, I NEVER saw anything above 15 minutes apart from last Thursday morning when it went to 40mins.
Ripsaw 20mins, Bluto 5mins, I think it's pretty accurate to be honest, although I would need to know how many people sending data there is in order to see if the average is credible or not.
For example, someone might have sent info for Hippogriff's 30 mins at 10am this morning. As nobody else is updating live, the wait time for Hippogriff still stands at 30 minutes, despite 8 hours having passed since the initial update.
It will get more reliable when more people begin to use it.