Every player carries rules of thumb. This chapter prices six of the most common ones against the solve — not as insults but as a bill: the average cost per deal of following the habit where it applies, and the single worst hand it ruins. The expensive habits are not the ones folklore warns about.
How a habit is priced
Each price is a one-shot deviation: at every node where the habit prescribes an action, we charge the gap between that action's certified match-win value and the best available action's, weighted by how often the deal arrives there. The unit is percentage points of match-win chance per deal — the same pp the lab's COST view and the eleven chapter use.
The bill
| Habit | Mean price, pp/deal | Worst single hand, pp |
|---|---|---|
| Accept every truco (10×10) | 10.4 | 36.6 |
| Fold every truco (10×10) | 6.2 | — |
| Accept every mão de onze at 11×9 | 26.2 | 63.4 |
| Fold every mão de onze at 11×10, dealing | 18.7 | 55.3 |
| Open with the manilha when you hold one (10×10) | 4.1 | 19.8 |
| Always open with your strongest card (10×10) | 1.2 | — |
The ordering is the finding. The dear habits are answering habits — how you respond to a truco or a mão de onze — and the cheap ones are leading habits. Always opening with your strongest card, the folk rule most often repeated, costs barely a point per deal; calling every truco costs eight times as much, and auto-accepting the eleven at 11×9 costs twenty times as much.
Reading the bill
The two eleven rows point opposite ways on purpose: at 11×9 the range snaps shut and the leak is accepting too much, while at 11×10 dealing the fold is under water (44.7%) and the leak is folding too much. The same instinct — “be careful at eleven” — is a virtue at one score and a 19 pp tax at the other. Score first, then cards.
The lead habits are cheap for a structural reason the opening-leads chapter charts: most hands have several openings within a point of each other, so even a dogmatic rule usually lands near the frontier. The traps are concentrated — the zap-led hands at ~20 pp — rather than spread. Answering decisions have no such cushion: accept and fold diverge by whole hands, not fractions.
Walk this spot in the lab:9x11 v4 →