This is the SRAM method - that's what they recommend on their web site, subtleties such as inner vs outer link aside; it's know as big+big + 1 (or 2, depending on the flavor of the moethod used). Shimano goes another way - big front, small rear, vertical alignment of RD rollers. At the end of the day, you still need to check that you can ride big-big without the RD being bent out of shape, and small-small without the chain sucking into the chainring.