Turning the engine by hand does nothing for the lubrication - as I and others have already stated, it's to do with checking for hydraulic locks and good compression, and in the case of the Gipsy for priming (with the LH cowing open you pull a toggle that holds the carb float depressed, and work the handle one one of the fuel pumps up and down 'till fuel flows out of the manifold drain, then 'suck in' to draw it into the cylinders).
I always worried about turning the Yak 52 over before flight. You have to do it because these radial engines are particularly prone to hydraulic locks, but it's a big engine and the gearing means you are turning the engine over faster than you are turning the prop. So it's hard work, and can't be done with an arm's length flick like the Chippy. You have to get in there and really heave each blade round. Nasty if it starts
SSD