The streak's shadow
Streaks are motivating. The visual continuity of a chain creates a commitment device: breaking the streak becomes psychologically costly. For frequency-dependent habits, streaks demonstrably help.
But streaks have a shadow. When maintaining the streak becomes the goal — separate from the outcome the streak was designed to support — they undermine the system.
Examples: a runner pushes through a minor injury to protect a streak and creates a significant one. A writer publishes low-quality work to keep the streak alive, gradually degrading the standard. A meditator rushes through two minutes just to log it.
In each case, the streak measurement divorced from the outcome it represented.
The distinction
Ask: is consistency the primary driver of the outcome I want, or is quality?
Use streaks for habits where frequency is the primary variable: exercise, hydration, sleep timing. Consistency is the outcome.
Use outcome metrics for habits where quality is the primary variable: writing, deep work, creative practice. A streak measures the wrong thing here.
The habit determines the measurement. The measurement should never determine the habit.
Steady wins.