It is well known among grey-haired old hot rodders like me that retarding the camshaft on a gas-burner will increase top end power but kill low end torque, whereas advancing the cam will increase the bottom end while lowering the top end peak -- lots of us used to have sets of offset Woodruf keys in our tool boxes to adjust the cam timing in various 427 cid super modifieds for varying track conditions.

I'm not sure that checking against the assembly timing marks isn't plenty good enough for keeping a watch on chain stretch, though, provided you know where your motor was at to begin with. Lots of the high end motors that I've worked on with vernier type of adjustable cam sprockets from the factory to allow for compensation for chain stretch (Maserati V8s and classic Lancias, for instance) just specified checking and resetting the cams by the marks at every valve setting -- but they were indeed assuming that they were set up right on to perfection from the beginning. To me, the factors other than chain stretch that would throw off the assembly marks, such as tensioner or sprocket wear, would also throw off the dial indicator method, and in the latter case, you might get fooled by cam and rocker wear if you weren't careful, too. The real key is being perfectly familiar with every individual motor and taking notes from one tune-up to the next.