At Disney World how long does it take the buses to come and get you?

I was wondering how long the wait would be when your waiting for a bus to come get you.For example lets say I was at Epcot and I wanted to go to Animal Kingdom.How long would I have to wait for the bus to come and take me to Animal Kingdom?And if I missed one bus how long would I have to wait for the next one to come and get me and take me to Animal Kingdom?I really hope some one knows the answer to this question and you answer it seriously.I really need to know!!Thank you for your time!