yeah, but when you dont want to waste another 30 mins, you'll waste them anyway when you're just lying in bed thinking about hands. I know what you mean when you're just grinding till late, but the next day you'll feel even worse after work, so it will effect your play even more (at least with me it does), so it's very important to keep to your schedule. It's off course easier said then done, but I usually try and put in some standard sessions during weekdays and then have a big one on friday night and some more during weekends if I can. It's all about finding a balance between work/sleep/poker and relaxing/having fun