Which prop rule taught you something useful for live?

[LondonScalper]

I've been fairly critical of some prop rules over the years, but I'll admit a few of them taught me something I've kept on my own account. Here's mine, and I'd like to hear yours.

The daily loss limit as a hard rule. I had a daily limit before, but it was a soft one. I broke it a few times a year. On a prop account breaking it means losing the account, so I had to follow it strictly. After a few months of that, I realised how many of my worst days were simply days where I'd kept going past the point I should have stopped. I now enforce my own daily limit with a script, exactly as a prop firm would.

Close to that, the weekend flat rule. I used to hold the occasional position over the weekend if I liked the setup. Being forced not to on a prop account, I noticed I didn't miss it. My weekend holds were a small part of my returns and a large part of my stress.

And I'll mention one that taught me the opposite: a rule restricting how much profit could come from a single day pushed me to trade more on quiet days to even things out. My results on those quiet days were poor. So I learned what not to do, which also counts.

What's a prop rule that changed how you trade your own money?

[Shadow Trader]

Mine is the trailing drawdown, measured from the equity high rather than the balance. I hated it at first because it punishes you for open profit you never banked. It ended up changing how I manage winners.

Say the trailing limit is 5% on a 100k account. A trade that runs to 1,500 in profit and comes back to break even has used 1,500 of your room, even though the closed balance didn't move. On a normal account that round trip feels like nothing happened.

After a few months of that I started noticing how often I gave back most of an open winner because I wanted the full target. Now I take partials at 1R on scalps that stall, and I track my own peak-to-trough equity each day, not just closed P&L.

Your script for the daily limit is the part I'm curious about. Does it lock you out until the next session, or can you switch it off? Mine can be overridden, and I've noticed the override is the weak point.

The single day profit rule did teach the wrong habit. I'd just say the lesson was about forcing trades in general, not that one rule.

[Shadow Trader]

Coming back to the point about the rule only working because breaking it cost you the account. I think that's the real lesson, more than the rule itself. Self-imposed limits leak because nothing happens when you break them.

What made my own daily limit stick was adding a consequence. If I override the lockout, the next day is half size, no exceptions. That is annoying enough that I've only overridden it twice this year.

The other prop habit I kept is measuring the limit in R rather than in money. A fixed dollar limit quietly gets looser when I cut size after a drawdown and tighter after a good month, which is the wrong way round.

At 3R for the day, I stop. It doesn't matter if that's three clean losers or one bad slip on a news spike, and it doesn't matter what the account is worth that morning.

The minimum trading days rule I'd put on your "taught me the opposite" list. Logging in to place a trade just to tick a day off is the same quiet day problem you described.