The 1% rule is simple: never bet more than 1% of your total session bankroll on a single spin. If you sit down with $500, that means capping individual bets around $5, no matter how tempting a bigger bet looks after a few wins or losses.
The reason is pure math, not superstition. Slots are built around variance — long streaks of small losses are entirely normal even on a fair, properly-licensed game, and a bankroll bet in large chunks can be wiped out by an ordinary bad streak long before the game's long-run RTP has any chance to play out. Betting $5 from a $500 bankroll survives roughly 100 losing spins in a row; betting $25 (5%) survives only 20 — a huge difference in how long your money actually lasts.
This matters even more on high-volatility games, where big wins are rarer and losing streaks run longer between them — pair high volatility with an even smaller bet size, not a bigger one. The 1% rule won't make a losing session profitable, but it buys you the number of spins needed for a game's statistical behavior to actually show up, instead of your bankroll disappearing in the first unlucky ten minutes.
