Very often. Usually it is minor items such as dents, fluid leaks, tyre damage, fan blade nicks, evidence of bird strike etc. Occasionally it can be more serious. I’ve had flap track fairings hanging off, turbine cracks, fuel tank leaks and lighting strike damage. In many places the “walk round” or pilots pre-flight check, is the only visual inspection that will performed. Far from an entire career, it would be unusual to go a month without something coming up.