Run it where you feel comfortable.
Other option is that next time you have the shock out, pop the linkage back together and run the swingarm through its stroke and take note of where the chain is tightest. Mark and measure in a specific area for your own records and you'll know what works best.
I just stick 3 fingers between the swingarm and slider at the rear. I find my chain is usually a bit on the slacker side.