The Difference Between a Rule and a Preference
Open almost any written trading plan and you will find two kinds of sentence sitting side by side in the same list. Some describe the conditions under which the approach is supposed to have an edge. Others describe how the person prefers to work. Both are written in the same imperative voice, both have a bullet point, and nothing on the page indicates which is which.
Why the Mixture Is Corrosive
A list where every item carries equal weight will be broken eventually, because some of the items do not matter enough to hold. You skip the one about reviewing yesterday's sessions before the open, nothing bad happens, and you have just demonstrated to yourself that the list is advisory. The demonstration does not stay attached to that one item. It generalises, quietly, and the next thing you skip is load bearing.
The reverse failure is just as common. A trader who treats every preference as binding spends their discipline on things that do not affect outcomes, arrives at the genuinely important rules already depleted, and feels like a failure over deviations that cost nothing.
A Working Test
Ask what breaking the item does to the trade. If breaking it means you are now taking a trade the approach was never meant to take, it is a rule. If breaking it means you took the same trade in a way you like slightly less, it is a preference.
A condition that the entry only exists after price closes beyond the range is a rule, because ignoring it produces a completely different trade with a different risk profile. A habit of drawing the range lines in a particular colour is a preference. Sitting down fifteen minutes before the open is probably a preference, unless your rule set contains something that can only be checked in that window, in which case it has quietly become a rule and should be written as one.
The Grey Cases Are Where the Work Is
Position size is the obvious example. Trading smaller than usual does not change what setup you took, so it looks like a preference. But if the plan's expected outcomes assume consistent size, then varying it changes the thing the plan is describing, and it is a rule. The category depends on what the rest of the document claims, which is why sorting cannot be done item by item in isolation.
Time of day is another. A stated cutoff after which no new position is opened is a rule if the approach depends on the character of the early session. It is a preference if it exists because you would rather be finished by then. The sentence looks identical in both cases. Only the reason separates them, and the reason is usually not written down.
Write Them in Separate Places
The simplest fix is physical. Rules live in one short list, preferences live in another, and the two are never printed on the same page. The rule list should be short enough to read in full while the range is forming, which is a useful constraint in itself, since anything that will not fit was probably not essential.
Preferences still deserve to be written down. They are how a session runs smoothly and they are worth keeping. They simply do not carry the same consequence, and pretending otherwise devalues the sentences that do. When you break a preference, you note it. When you break a rule, you have taken a trade outside the plan, and that is a different kind of entry in the journal.
Reclassification Is Part of the Process
Items move between the lists over time, and that movement should be deliberate rather than incidental. Something you thought was preference turns out to change your outcomes, and it gets promoted. Something you enforced rigidly for a year turns out to make no difference, and it gets demoted rather than deleted, because it may still be a useful habit.
What should not happen is silent reclassification, where a rule gradually becomes optional through repeated small exceptions and nobody ever decides that it did. If the list is going to change, change it on purpose, at a moment when no trade is pending, and date the change so you can tell later whether the plan you are following is the one you actually chose.