A betting strategy built on martingale doubles the stake after every loss, so that one win recovers everything lost plus the first stake. On paper the plan cannot fail; in practice a run of six or seven losses, which comes sooner than people think, asks for a stake sixty or a hundred times the first one. Table limits or the bankroll end the sequence long before the promised win comes.
Bankroll management units turn that share into a number. One unit is usually one or two percent of the bankroll, and every stake is counted in units: a normal pick gets one, a strong opinion perhaps two, and never ten. Counting in units makes results comparable across weeks and bet sizes, and it shows at a glance when stakes have started to drift upward after a winning or losing streak.
Bankroll management starts with a separate sum set aside for betting and never topped up from rent or savings. The core rules are short: decide the bankroll once, stake a small fixed share on each bet, never chase a loss with a bigger stake, and review the plan on a set day instead of after a bad result. Written down before the first bet, those rules do more for a bettor than any tip ever will.