The first thing to notice about playing dozens (and the same applies to any roulette column betting strategy) is that it is a higher risk bet than 50/50 bets like red or black. If everything played out like clockwork, you would only win every one in three spins of the wheel – and add the problem of a zero landing, negating your bet.
So, by using the same betting strategy as you might for 50/50 bets, you are likely to lose quickly; you cannot possibly expect to win enough times to make any money. You can, however, adapt the most common 50/50 strategies to make a solid roulette dozens system. The best-known 50/50 strategy is the Martingale System. On 50/50 wagers, like red or black, you double your wager each time you lose until you win, and then you start back at one unit again. (資料來源 )
