We see the failure logs every day. Same five mistakes, in roughly the same order, account after account.
This isn't a list of trading mistakes (overtrading, no stops, FOMO). Those exist on every blog. This is the list of structural mistakes specific to prop firm challenges, which is where most traders actually fail.
Mistake 1: Sizing for the win, not the loss
The first thing a new challenge trader does is open the configurator and ask, "what's the cheapest account that lets me hit the target fastest?". That's sizing for the win.
The right question is: "what's the largest account where my normal stop is 0.5% to 1% of balance?". That's sizing for the loss.
A trader with a $200 stop on a $25K account is risking 0.8% per trade. That same trader on a $100K is risking 0.2% per trade. Same skill, two completely different failure rates.
For the contract math behind this, see micro vs mini futures.
Mistake 2: Treating the max loss as a stop
In the challenge, the Max Loss Limit (MLL) is a hard breach line, not a stop. Hit it once and the run is over. (Once you're funded the shape changes: crossing 4% cuts your split instead of ending the account, and 8% is the line that ends it.)
Yet traders consistently size as if they have the full MLL to spend. On a $50K challenge, that's $2,000. They take a $400 loss, then a $400 loss, then a $300 loss, and now they have $900 left for the rest of the run.
The fix is a soft daily stop set at one third of MLL. On the $50K, that's $665. Hit it, walk away.
For how the MLL line actually moves, see trailing vs end-of-day drawdown.
Mistake 3: Trading every session
A Rev One challenge runs 30 days and you can extend it whenever you want. There is no "I have to trade today". Yet the data shows traders averaging 4 to 6 trades a day for the first two weeks, then collapsing.
Trade two days a week if your edge is in two specific setups that show up twice a week. The challenge only asks for 2 trading days. On the funded side there's no trading-day minimum at all, just 5 profitable days before a payout, counted per cycle rather than per week.
Mistake 4: Revenge after a red day
Look at the equity curve of a failed challenge. Nine times out of ten, there's a red day, then the next day's PnL is the largest absolute number on the chart, in either direction.
The red day did not cause the bust. The next day did. The trader sized up to "make it back", and the size was the bug.
The fix is mechanical: the day after a red day, your position size is halved. Not "felt", halved. Hold yourself to it for the rest of the eval.
Mistake 5: Ignoring the consistency rule until it's in the way
The Rev One challenge has no profitable-day requirement. It has a consistency rule: when you pass, your single best day can't be more than 50% of your total profit.
Sounds easy. The data says otherwise. A trader clears half the target in one session, then has to keep trading purely to dilute that day. They're already near target with nothing left to gain and a live max loss line. They oversize. They wash out.
Plan the shape of the run from session one. Aim for four or five moderate green days rather than one big one, and the 5% target arrives with the consistency check already satisfied.
Profitable days do exist, but only on the funded side: five per cycle, each clearing your size's daily minimum. For those mechanics, see the profitable day rule explained.
The fix is a one-page plan
Before you start an eval, write a one-page plan with five lines:
- Account size and the dollar value of MLL.
- Risk per trade in dollars (0.5% to 1% of balance).
- Daily soft stop in dollars (one third of MLL).
- The largest single day you'll allow yourself (under half the profit target keeps the consistency rule out of your way).
- The rule for the day after a red day (size halved).
Tape it to your monitor. Don't trade without reading it.
For the full pass framework, see how to pass a futures prop firm challenge in 2026.
The traders who pass don't have a special edge. They have a written plan that survives day three.