From the Coach guide
Focus is an app measure of plan follow-through.
Focus counts completed runs and checks effort when the data allows it.
Completed sessions
Completed and partially completed runs count as logged. Today's and future sessions are excluded.
Effort checks
Effort can be judged only when a matched run has heart-rate-zone data and the session has target zones. At least 75% of measured time must fall within those zones to count as on target. Missing effort data is not counted as a failed effort.
Strength sessions
Each scheduled strength session counts as 50% of a run. Suggestions do not count against you. The main count shows runs only.
Status cutoffs
On plan means at least 80% weighted completion and, when effort can be judged, at least 70% of judged runs on target. Off plan means below 50% weighted completion. Drifting is the remaining range.
What this measure is
These cutoffs are app display choices. They are not scientific measures of discipline or health.