What counts as “on time”
The decision that changes the result is the window. Is a monthly inspection done three days late compliant? A widely used rule is a window of 10% of the interval: about three days for a monthly inspection and about five weeks for an annual one.
What does not count is a work order closed without the inspection being done, or one rescheduled so many times that it slipped into another month.
Why it matters beyond maintenance
If you maintain customers’ equipment, it is the number you bring to the renewal meeting: what the contract committed to versus what was done. If you maintain your own, it is the first sign that the plan does not fit your team’s hours.
Compliance that drops month after month is rarely a discipline problem. It is almost always a preventive maintenance plan sized above real capacity, and it shows in the backlog too.
The usual mistake
Measuring it against what is left in the plan at month end. If postponed inspections move to next month and drop out of the denominator, compliance looks high while the plan falls apart. Count what was scheduled at the start of the period and keep a trail of every postponement.