I run mine at the maximum recommended pressure listed in the shop manual and check 'em before each trip. If you run over the maximum pressure, as the tire attains operating temperature over the course of a few miles, the internal pressure climbs up a fair amount, probably 6-7 pounds over the maximum cold pressure which is why tires should always be checked 'cold', not after being used. The manufacturer arrives at the inflation figures through sound engineering principles based on speed, weight of the vehicle, tire construction and rolling resistance. With tires, especially on a bike where your life may be depending on that tire under your butt, I don't fiddle.
It's a good idea to do a visual check of your tires before each trip, checking the pressure, inspecting the tire for cuts, tread separation, sidewall bulges or cord movement and tread depth. For most riding conditions you need a minimum depth of 2/32" of tread depth measured in the center of the tire (or more). While you are down there looking at the rubber, check the hoop too. Look for cracking as well as deformed edges where the tire seats on the rim you get those hitting Michigan potholes.