Pattern Rodzik singles out at the end of the talk: `Time.current` (or `Time.now`) looks simple but is functionally a random source — every caller gets a different value. Ruby developers reach for RSpec's `travel_to`/time-travel helpers to control it; Rodzik's original claim is that time travel is the 'only option'. An audience member challenges this and suggests two alternatives: algebraic effects, and dependency-injecting a current-time object per request/process. Rodzik agrees both are better but notes time-travel helpers still pervade real codebases.