You decide. Both players have an edge of 6%. Both players have the same $1,000 bankroll. Player one flat bets $50 per spin for 10k spins (plays off an on over a month) and wins...$30,000 but along the way has a reasonable chance of losing his entire bankroll before he can win the full $30k. Player two bets just one percent of his bankroll at each spin. His initial bet is just $10 and he has very little change of going broke before playing all 10k spins because he can theoretically nearly infinitely subdivide his bankroll in the event of a losing stretch. In the end he wins approximately $403,000! Mathematically it makes the most sense to run the progression that bets a percentage of your bankroll because it enables you to take advantage of the compounding interest like effect! The idea bet is (edge/expectancy) x (confidence level) = Bank to bet ratio.