I have never had any issues with the quantity/volume limits on alcohol in checked bags, either domestically or internationally. (I've also never had issues with customs limits on the same, but that's a separate topic.)

I routinely fly with 2x 60-70lb suitcases of alcohol brought back from trips, and know someone who travels with that much around the world to share on pretty much every trip he takes. TSA sometimes opens the bags and leaves a note, but I have never had them confiscate or lose any contents. Once they even did a better job wrapping back up a couple of bottles I'd packed, adding some extra bubble wrap...!

In the past couple of weeks, I brought back a couple of cases of tallboy beer cans in one bag (from Treehouse and Trillium on a MA trip) and a Yeti backpack (inside a lightweight suitcase) full of bottles, probably 3-4x 750s and 6-8 500mL bottles. No worries at all. Sometimes, I have to move a few things between bags if the airline agent sees it being 71lbs, for example, but that's about it.