Coincidently, I used my "can" for the first time two evenings ago. I saw a deer about 100 yards off, so I grunted a few times. This got the deer coming towards me. It turns out, it was a doe that responded to the grunt (she must be getting close to being ready). She was a smart older doe and she saw me in the stand and although she didn't bolt, about 40 yards out she decided to circle me to get my scent. It was real thick on the route she took and I don't shoot that far anyway. After about 10 minutes I decided to give the can a flip. I bleated twice and put it away. About 30 seconds later a nice large buck came down the same trail the doe had taken. He was running with his nose down! He just knew that doe was calling his name. Unfortunately he took the same route she did, and never came within range. I tried the can again and grunted, but the buck thought he was already on the right trail. He wouldn't come in. About 5 minutes later I see the doe sprinting back on the original trail, I assume in an attempt to get away from the buck. I'm guessing he was overly assertive when he finally caught up to her.

Anyway, this convinced me that this is a great aid during the rut or immediately before it.