Hydraulic lock is a potential killer. I used to fly a Yak52 (Vendeneyev 9 cylinder radial) and it had to be pulled through before start. And if it hadn't run for more than a couple of days, the drain plugs in the inlet manifolds had to be removed else the oil that collects there would be sucked into the engine on start, giving a 'lock'.
If you are lucky, that destroys the engine and you get your cheque book out. If you are unlucky, you are unaware of the 'lock' and it just bends a con rod. Thatbent con rod will fail at some time in the future. That's what kills people.
Our Chipmunk is always pulled through pre-flight, to check compressions (valves can stick in the Gipsy engine), to check for impulse mag click (if it doesn't click it will never start and the mag needs a clout with a hunk of wood to free the stuck impulse) and to check for hydraulicing.