Bonez: Yes, that is a good habit to get into....especially if you are letting the bike sit for weeks unused. Finding TDC on compression closes the valves tightly and releases as much tension off the valves springs as possible. How much this saves on preventing weaking of the springs is anyone's guess. Here's a reason why it's good practice to close the valves everytime the engine is topped. My son rode his XR100 one afternoon and then washed it. Evidently, water went down the exhaust
pipe and got on the exhaust valve stem because he didn't know to move the engine through to TDC. The bike sat up for a couple of weeks and when he went to start it, the exhaust valve had seized in the head and the piston came up and hit it....bent the valve badly. Dad(me) had to replace the valve and seal. Since then, I ALWAYS put the engine at TDC...even between motos and practice.....ALWAYS!