Our 60x100 shop has tin around the inside, but I've never noticed an echo. The ceiling is a soft insulation (fiberglass blanket with a white plastic surface) and maybe that is absorbing some of the sound.
The tin on the walls isn't perfectly flat with ribs. There are 3 angles between the ribs, which should help to deflect the sound in different directions.
I once toured a Gateway computer facility in Kansas City, and they used tin on the ceiling to kill the sound. The tin was perforated, and it really soaked up the sound.