Hi!
I know this question was asked a while back, but for anyone who still doesnt have a great answer, check the switch container property editor of "Footsteps" - in the "Advanced Settings" tab, there should be a "Limit Sound Instances" tab that will limit the number of times a sound for the footstep can be played.
Going from Wwise 101 Lesson 3(ish?) to Lesson 5, I think within the preloaded Wwise projects, one had this "Limit Sound Instances" checked and one didn't - the footsteps were way too fast in Lesson 3 and way too slow in Lesson 5 - I found that setting to be the issue.
Will H.