How do you know what side the whole in the foot is going to spawn. i'm on solo and i find that i'm always picking the wrong side and i can not make it to the other side in time. also it takes like 10 min. for the same robot to even spawn. if there isn't another way to tell which side it is besides checking under the foot then i believe that Treyarch zombie team did not test their game but whatever. Waiting for many things seems like a major problem in zombies. I'm sure I didn't need to point that out but whatever.
When 3 of them patrol no feet are open.
Try to be ready for them, look before they approach you as they just enter the map and you should have no issues. If you still having a hard time then practice on the middle one as he is the easiest to get in to by stamina or jug.
when 3 robots come one foot in any of the 3 will be open. just take ur time and ull get it. on all of them there is enough time to get to the other if need be