I have a good amount of time in 172's (N-S models), the Baron BE55A, the Debonairs, and F model Bonanzas. The 172s won't quit at the min ground idle as long as you don't lean it out too much for taxi. The Beechcraft birds will and even at full rich at ground idle when cold. Almost all post-start checklists have you set the power to at least 1000 RPM. The Bonanzas and especially the Baron are relatively slow to decelerate on approach, especially if you don't have the flaps or gear out. I would guess that the low idle stop for the Beech birds are set lower than a typical training aircraft like a 172. I also suspect that some schools might ask their mechanics to bring the low idle up just a hair, so that new PPL students won't decelerate too fast in the flair when they are learning how to land.
Edit, as Nick said. 750 rpm is way too high for low idle.