She obviously is very smart and knows when she want to go fast and when she doesn't. hehe. she sounds like a lil firecracker.
she has you trained very well.
I hope others will chime in with experience as two of mine walk and walk and one is in stroller. lol she will freeze as soon as you put the leash on her harness and not move one inch. Lola has me trained well...she even gets picked up from bed and carried to her potty spot every morning and she will wait on the bed until I scoop her up and let her out!!! hahaha