Yet another quote from the "Beer Manual"
The ideal gauge pressure for a beer is the pressure
at which CO2 is not diffusing from beer into the
headspace and excess CO2 is not absorbing in the
beer. This value varies from account to account depending
upon factors such as temperature...
Not a home brewer, but we serve LOTS of craft beers, and build and maintain our own keg equipment. I see lots of questions on the forums concerning correct keg "gauge" pressures, beer line diameter and length. The Brewers Association Draught Beer Quality Manual...