7th...Say you have 100 stamina so you can do 2 after you wake up, that leaves 5 more. 5*50 = 250 stamina which regens at a rate of 1 stamina/3 min, so you need to wait and play each time 50 stamina is available. Which in turn means waiting a total of 750 minutes or 12.5 hours.
That's a damn long time to get 3-4 more runs of Shura, just saying.