Bankroll and discipline: variance, stake selection and the length of a session
Variance, stake selection and the habits that keep a player at the table.
Poker pays out in a scatter rather than a stream. Two players making identical decisions across the same number of hands can finish a stretch far apart, and neither result on its own says which of them decided better. That scatter is variance, and it is a permanent property of a game where the best hand does not always win and the winning hand is not always shown.
A single hand has an enormous range of outcomes and only one of them happens. A session is a few hundred hands, which is enough for the scatter to dominate and not nearly enough for skill to separate from it. This is why a losing week is uninformative and why a winning week is equally uninformative in the other direction. Neither is long enough for the underlying quality of the decisions to be visible through the noise.
The practical consequence is that results are the wrong thing to review. The right thing to review is the decisions: the spots that were unclear at the time, the hands where a rule of thumb was applied without checking whether it fitted, and the calls that were made because the pot was large rather than because the price was right. Those can be examined immediately. The result cannot.
Bankroll & Discipline
Variance is not bad luck, and a downswing is not a verdict
A run of losing sessions tells a player almost nothing on its own. What it should change is the stake, the session length and the review, in that order.