If you just built your motor or had previous problems I understand...but why waste the time? If my boat ran flawless Fri., Sat. and Sun. then parked in my driveway...why check to make sure everything is ok the next weekend?...Sure, next time at the ramp I will make sure water is coming out the exhaust upon start-up, but other than that, I have trust in my motors. If you can't trust your motors...you likely used the wrong builder.
Its called standard maintenance...new impellers every two, and new plugs, wires, caps and rotors every year. If it needs it or not, it is standard maintenance. At 600 hours, new rings, bearing, re-do the heads if they need it or not.
Although, if I lived two hours from the ramp, I would likey make sure they at least turned over.