When a novel interaction or architectural decision has no established precedent, explore several concrete alternatives before implementation. Building the wrong thing costs more than exploring three options.
The rule: When the right answer is not obvious, build 2-3 competing prototypes or sketches. Compare them side by side. Only then commit.
When it applies:
Novel UI interactions (no prior art in the codebase)
Architectural choices with multiple viable approaches
Product design decisions where user experience depends on feel, not logic
When it doesn't:
Mechanical implementation where the pattern is established
Bug fixes or refactors with a clear target state
Changes where constraints dictate a single viable approach