To tell the truth, I have always found back-counting at
any game to be problematic. I am talking about traditional stand behind a table counting and jump in. Some of that was bad timing on my part. When I was based on the east coast I was playing very low limit and tables were very crowded. There was rarely an empty seat at the low limit table(s) and if there was....nothing worse that back counting and have someone "gobble up" the empty seat or 2 just when the count became worth jumping in.
When I moved to Vegas, I was playing green and there are plenty of empty tables. Back counting and spreading to multiple hands were two techniques I though I would be able to employ a lot of and neither worked out, for different reasons. For back counting, while I know others do it, or say they do it, even here in Vegas, I just have found standing behind a fairly empty table with 1 or 2 players looks suspicious. I only takes a few seconds before both pit and other players notice you usually. They might not say anything, but you are noticed. And I am sure by surveillance as well.
So my back counting has been limited to two experiences. 1.) is just walking through a casino and seeing a bunch of small cards on the felt. Depending on just how many small cards I may jump in but if it is only one or to players, I might need a second round of positive count (small cards coming out) to hit my threshold. I can get away with watching for 1 round.
My second senario and one that I employ a lot, usuall a couple times a day, is counting or (back-counting) a second table while playing my primary table. That really has become my specialty in back counting. It is sort of a blend of "play-all" that allows you to play significantly more rounds at positive and max bet counts.
I play mostly shoe games so that is sort of what I consider my specialty. But I play a bit of double deck too and I have to agree with Don, I see very little opportunity to back-count on double deck. Maybe that occasional "walk by a table" scenario already mentioned, but by the time you jump in, you get a round or two. Seems like a lot of "scrutiny" for a round or two.