Oil, fluid and O2 levels are checked in advance of our flight requests, however, I will never board the aircraft without doing a 360 walk around.
I have no idea whether somebody has tampered with the aircraft, or run into it with a vehicle, or a perhaps a mechanic forgot to lock a cam fastener, or a medical crewmember plugged an extension cord in or left the baggage door unlocked, or sombody walked under the tailboom and broke an antenna.
Of course you have to do a walk around. And "strive" should be the most that any of us offers a customer.