My dad trained a lot of horses in his younger years and used this technique on several occaisions. I don't believe it was used with every horse though, but more on certian ones that showed a tendency to buck a lot.
I wasn't around when he was training all of those horses, but he trained our 3 Walkers and they were great horses. Well mannered, respectful, plenty of spirit, great on the ground and in the saddle. The kind of horses who did what you asked with a good attitude. Of course, they had their moments too. Especially after 6-8 months off during the winter, spring was always an interesting time.