Mr Viper, 3 times a day when it's a double day, otherwise say twice a day on a rest day/long run only day.
Morning, and after each run generally.
A lot of the moves originate after hip/back and glute niggles, so I fear them coming back if I don't keep it topped up. An Oesteo told me to do his stretches twice a day, but admitted if I did them more it would strengthen quicker, so I did! It's a bit of a balancing act I guess, whereas in the past i'd strengthen the weak area until it felt fine, then scale it back down.
Certainly keeps me ticking over in good form though, but I could do with feeling "ideal" again 
I remember hearing some fitness trainer saying he stretched for hours each day once. I thought that was mental at the time, but for intense sports where pure flexibility is needed i can believe it now. I doubt many of us on here are too flexible, not many runners are.
Edited: 07/11/2012 at 09:47