My Winnebago came with documentation to keep the pressure at 45 psi. The new pumps out there are set at 55 psi from the factory. I contacted Winnebago to ask if that was alright. Winnebago's response is that is fine to set your pump at 55, but keep the shore line set to 45. When other people on the shore water turn off large loads, that can cause a type of water hammer that momentarily raises the water pressure. With the shore water set at 45, you are safe from that effect. The pump doesn't have that phenomenon, so it is OK to set it at 55.
Of course, if you have a quality regulator like a Valterra or Watts, the pressure surge shouldn't make it past the regulator, I would think.