The only time I bleed the pressure on the keg, through pulling the pressure relief valve, is if I've had high pressure on there (more than 10, as in 30 or so) to force carbonate, and then hook it up to service pressure. (10psi) I don't have check valves and I don't want to run the risk of sending beer to the regulator. Other than that, nope. just hook 'er up.