When I take Moggie(my blackthroat monitor) out on a leash, it's not me taking her for a walk. It's me with a leash to make sure she can't run off. I bascially follow her with a 20 foot lead so she can wander some. Only once in a while.
Monitors are not exactly pet-pets. They are more captives.
There are people who seem to routine take their lizards out on leashs, and maybe they are the exception. Who knows what goes on in lizards' brains?
In general, I wouldn't suggest that a monitor would enjoy being walked though. Especially being told where they SHOULD walk.
Wolfy