Rules of thumb for buy-in, bankrolls, etc.

I'd like some of you sharks and old timers to look over my numbers. I want to work out some rules of thumb for myself.

Say I'm playing 5-10 limit hold'em.

I understanding is that you want to buy in at a table with 25x the big bet. In the case of a 5-10 game, that would be $250.00 (or $2.50 in a .05-.10 game). This way, you can absorb a bad beat or two and still have enough money to play your way back into the black.

I also understand that the rule of thumb for total bankroll is 300x the big bet. Again, in a 5-10 game, that would be $3000.00 total bankroll (or $30.00 in a .05-.10 game). This is so you can absorb those inevitable streaks where you finish in the red several days in a row.

Are these assumptions correct? Should I buy in with closer to 50x the big bet? Is $3000.00 a big enough bank roll for playing 5-10 limit hold'em?

Now, what I'm really wondering about is profit taking at the table. When do you "take the money and run?"

Everything I've read so far says keep playing so long as you can still play your top game. Examples of players playing for 24-72 hours or even 96 hours straight are then given.

Personally, I think that's nuts. IMNSHO, if you play for more than 14 or 18 hours in a session then you seek professional help. I constantly remind myself that I'm playing poker for the money, not for the action.

If 8 hours of back-breaking work a day is enough for my former boss ol' Mr Grinchly, then it seems to me that 6-8 hours of play a day is enough for someone trying to make a living playing poker.

So if I'm playing 5-10 limit hold'em and I sit down with $250.00, when should I get up, cash in and go home for the day?

If I made $100.00 profit (after rake and toke) then that would be 40% return on my initial $250 buy in. Any business manager will tell you that 40% return on an investment is AWESOME and you should be happy with it. I kind of lean that way myself.

But the fact of the matter is at a large, loose table I could fold and fold for an hour, blind down to $200.00, then in my first hour of play hit one monster hand for $200.00. Even after the rake and a generous toke I'll have made back my blinds and be at the 40% profit mark. In one hand. After just one hour of play.

So it suddenly doesn't seem compleatly unreasonable for someone to buy in with $250.00 and double his money in a single 6-8 hour session. Except that the expectation of doubleing you money every day is a perfect example of the "sucker mentality" that keeps people playing poker for 36 hours with money they can't afford to loose.

So that leads me back to just playing for $100.00 profit a day. That really doesn't sound like much. And when you concider it as profit off your total working capital of $3000.00, it actually comes out to be just over 3% profit per day. Doesn't sound like much at all.

However, when you spread that over five days of play a week, four weeks a month (20 days a month of play), and account for 5 days a month where you'll have several bad beats and end up in the red those day, that's $1500.00 profit for the month off your total working capital, or 50% profit. Monthly.

I'd like some of you sharks and old timers to look over my numbers. Do they make sense to you?