Okay, so this started as a napkin thought. How do you rinse prop firms? And the honest answer is that it's a simple equation. Time to pass, probability of passing, cost of evals. That's it. Three variables. But when you actually sit down and formalize those three variables, a whole system falls out of it, and that system is worth walking through properly. So that's what this post is. THE FORMULA Per attempt, the expected value of an eval is simple arithmetic: EV per attempt = p x payout, minus cost p is your probability of passing. payout is what the funded account is actually worth to you, and note that this is not one payout, it's the expected cumulative payouts before you eventually breach the account. cost is the eval fee. But per attempt is the wrong lens. The number that actually matters is: EV per day = (p x payout, minus cost) divided by T where T is the time it takes to resolve an attempt. Pass or fail. And this one division changes everything about how you should think about evals, because your eval fee is small. Your time is the expensive input. The bottleneck on rinsing is not capital, it's throughput. WHY SPEED WINS Here's where almost everyone gets it wrong. The retail instinct is to maximize p. Highest win rate, safest pass, tiptoe to the target. Feels responsible, right? But a pass rate means nothing on its own. What matters is what that pass rate earns you per day it takes to get there. A 70 percent probability that takes 40 days loses to a 45 percent probability that takes 12. Run the division yourself, it's not close. The riskier setting wins even though it fails more often, because it resolves three times faster and lets you go again. Think of it like a card counter at a casino table. The counter doesn't optimize for winning every single hand, that's impossible anyway. The counter optimizes hourly rate. Hands per hour times edge per hand. The eval fee is your table buy-in, and EV per day is your hourly rate. Speed is not recklessness here. Speed is literally what the formula tells you to chase.