We use it, as recommended, in the IFBP area in Africa - that's most of it! Works well especially as our company often flight plans the northbound and southbound a/c on the same airway, not that there are may to choose from. It's much nice, and safer, to see the other guys 1000'/4nm away rather than 1000' directly above or below.
On the North Atlantic tracks it's less clear if there is any benefit unless you are in proximity to someone else. However, our company suggests an offset, or not, so I tend to go with the plan. Put it this way, if something did happen and I hadn't offset the first question, over tea and biccies, would be why not. Apparently it's what Nav Canada and Shanwick like to see.