I'm all about saving every ounce of fuel too, especially in my old steed that didn't have any to waste in country. Geometry is how you do that though. The missing ingredient with some tankers is being predictable. I take a radar lock out at range, see them right on the line on a long leg in left hand flow, and I am going to work the geometry to join them on the crosswind/short turn with auto throttles set at 250 knots. Then they inexplicably turn hard super early and now are pointed directly at me. I take an offset to build some turning room to once again use geometry, and then they hot nose me all the way to a high aspect pass. Yes, our aircraft have technically reached one another in a shorter amount of time, but now I have to do some crazy hiyaka turn, roll out either 2 miles in trail and have to run them down, or if I time it perfectly, I end up a couple miles abeam on the outside of the turn (unless I also go full AB and do a 6-7G join, not exactly fuel efficient). So it ends up taking longer, and requiring more fuel since I am now jockeying the throttles, than it would have had they just maintained their published track in a predictable manner. Granted not every crew is this way, but a lot of the guys who have just started their 30 day "deployment" didn't get it.