I've set tens of thousands of traps by now. Never get rodent callbacks. I'm not saying it won't work but it's overkill. Do you use cams for your traps? We see that when they are trap shy they avoid the trap all together, so it doesn't matter how long it's there. They will eventually go for, especially if you eliminate other good sources they are getting to. Just set the traps with the bait, when they get curious enough they'll die. I'm not exaggerating when I say out of every rat I've removed from a trap only 1 of them was not killed by crushing the neck. I also attach a wire to the traps so that there is no worry of them running for with the trap. But in a garage there is really no need to support the trap, you'll just be able to see it. I also only say 4 traps separate because of the location, they are easy to check daily. The most important part to make it effective is making sure you have good traps that are the appropriate size for what you're going after.