I change my tire pressure almost every time I ride - depending on where I ride.

26x2.35 210 pounds Trance FS bike

32psi on sharp SoCal rocks (really sharp and jagged) = pinch flats 45psi = bounce off stuff and loose control 38 to 40 psi=great

35psi on fast SoCal fireroads/open trails=pinch flats 45psi=good control but some bouncing 50psi=really fast, low rolling resistance but bouncy

34psi in Pacific NW roots and soft mud=OK traction 30psi=better traction 40psi=slip and slide