How do I practice type system?

The most direct way to practice type system is through a focused exercise: Pick one field, category, or label you use regularly in your work or personal system — a task status, a priority level, a project phase, a contact type. Write down its current 'type': what values are allowed? If the answer is 'anything,' define a constrained set of 3-5 valid values. Then audit your last 10 entries. How many would have been caught or corrected by the constraint?

Common pitfall: Over-constraining too early, before you understand the domain. A type system that rejects legitimate inputs is worse than no type system at all — it trains people to work around your constraints rather than within them. The discipline is knowing when you have enough signal to lock down a type and when you need to leave it open for another iteration.

This practice connects to Phase 12 (Classification and Typing) — building it as a repeatable habit compounds over time.