I have found that being a professional trader is similar to being a professional salesman whereas your final results are about 60% dependent on your action and 40% dependent on the product you're selling/trading.
I think this is the same for myself. Its difficult to make money in a crazy whipsaw market just the same as it is in a watershed month such as Oct 08, but I think that programs such as Dan's good for the following reasons.
1) Perspective. What should you expect, what should you hope to gain, when is it time to get out of a position because your earlier expectations of either the marker or your position are no longer possible to meet. Trading is a skill set, similar to cooking. Your broker is your kitchen, and they might give you some great tools, but that does not make you a French chef.
2) Risk management. The market will move, guaranteed. Assuming you have no idea where its going on a tick by tick basis, how will you react. Its easy to build a risk management habit, but sometimes its good to bring it together into a whole portfolio management program.
3) Community. I've studied the market since I was in grade school and I also have a BA in Economics, so nothing in derivatives trading was totally new to me, however, you can spend years gaining knowledge and the above mentioned perspective, or you can get down to business and bring yourself up to speed in a more organized and speedy fashion. So what's time worth... to each his own. There is nothing Sheridan will teach you that you can't get from reading a series of books and spending hours on the internet, but when I signed up for his program I was looking for the inferred perspective from an experienced trader, not explicit advice from books. I want someone who will say 'um...well... I'm not sure if I would be comfortable with that' when I come across a new trading idea. Some people don't need or care for that, but for 6K, its a small investment to start one of the best businesses you'll ever find.
(now that i'm done blabbing, I should say that I'm not affiliated with Sheridan's program other than a student.)
Good luck, let me know how it goes.