[Mark McLeod]

Teleop MUST execute and complete/exit in less than 20ms, otherwise you will lose driver control.
It has to do this to keep up with the driver commands flooding in from your drivers.

If you call a sub vi that delays or add a delay of any kind into Teleop that is more than that 20 ms limit, then your driver's will begin to lose control as their command packets start to get dropped while the robot continues to do what Teleop was last told what to do.
For small time skips the drivers will start to notice slow or jerky robot reaction.
If you use the default Safety Config on the drive motors, then your robot will jerk to a halt after only a tenth of a second. Manipulators that are in motion will continue in motion and not be able to be stopped until your delay in Teleop finishes and Teleop is allowed to process the driver control commands again.
If you delay for really significant amount of time (seconds) and the Safety Config is not used, then the robot will continue driving on it's own according to what it last heard before you hit the button that started the sequence.
With no driver control that probably means crashing into a wall or your alliance partners.