I can attest to it too, I was feeding my fish 2-3 times a day and then i started fasting him for 2 days after a water change and his head is starting to pop.
I don't know about little tanks but i have heard the keeping them in taller tanks help's. Also the stressing part is more of an aggravating such as putting a mirror on the side of the tank so the Fh can fight with it for some parts of the day and full time will probably stress him since he doesn't feel like he is winning the fight haha.
Fasting a flowerhorm specifically a kamfa based fish will produce massive KOK growth if done properly. This is a very popular technique with sellers and most fish you see on aquabid have been put though a mini rutual witch pics at maximum growth.