Defined themes, defined rules. Outside the lanes is opinion, not doctrine.
The doctrine recognizes specific LEGO themes where the audience-first thesis, the minifig multiplier, and the maturation curve consistently produce 250%+ net ROI. Buying outside these lanes is allowed but doesn't carry the doctrine's backing — it's at your own conviction.
Discipline. Without defined lanes, every shiny new set looks like a potential winner. With lanes, you can scan a catalog quickly and discard 80% without analysis. Focus is what makes the doctrine repeatable.