I've found some pitchers like to have something like this to practice with and to use during BP. The squared off area in red is pretty neat for teaching young and old alike to be more dynamic with their targets. Like up inside, down inside... etc.
I think their a good idea.
However, avoid securing them in the ground (outside) with stakes and hooks that are shoved into the ground and similar devices.
These things have a tendency to get lost on the field when their plucked out of the ground. And when grounds keepers use grass cutting equipment, these things can get picked up and end up as projectiles. (the stakes that is.)
Any time I've had to use stuff on the field that required securing to the ground... I've used weighted objects. A good thing to use is to get an old fire hose in sections - about three feet each,, or a heavy duty bag, then fill either of them with sand and secure the ends.