Did you know there is specialty black paint available that absorbs *even more* photons than regular black?
True that.
I would think the closest I have gotten to "hard grown" is the succulents I installed in the park, which are growing in nutrient poor alluvial soil in nearly day-long sun, with zero irrigation (and only 5-8 inches of rain a year in recent years, none at all in the summer). The public garden closer to home is a similar situation (very rocky soil, nearly day long sun) and I don't water any of the big agaves out there at all. So yes, those two locations would qualify in my mind. If I didn't treat the agaves out there with total neglect, they would make even more pups and become even more gigantic, so growing them hard is actually a defined objective, and one I would recommend to anyone with a giant offsetting agave in the ground.
Most of the plants on our rooftop patio that receive nearly day-long sun are growing hard, if you were to judge them by their form, even if they do get a trickle of regular nutrients and weekly water. Limiting container size does affect the outcome there too, but the sun does sort of dominate in that situation.
