A maintenance programme is not one strategy applied to a site, it is three strategies allocated across assets, and the allocation is the actual decision. Run to failure, preventive on an interval, and predictive on a condition reading. Every site runs all three whether or not it says so, and the ones that run well have chosen deliberately which assets sit in which. The choice is made on consequence and on whether the failure gives warning, not on how modern the strategy sounds.
Run to failure is a legitimate choice
For a cheap, non-critical item with a spare on the shelf and no safety consequence, waiting for it to fail is the correct and cheapest strategy. Making that an explicit decision rather than an oversight matters, because an explicit run-to-failure asset has a spare available and a documented decision, while an overlooked one has neither.
Preventive suits failures that come with age or use
Where wear accumulates with time, cycles or distance, an interval catches it. This covers most of what a building or a fleet contains and much of a plant. Its weakness is that it does not detect a failure developing between visits, which is exactly where the third strategy earns its place.
Predictive suits failures that announce themselves
Vibration, temperature, oil condition and current signatures change before a failure. Where the warning exists and the asset matters enough to justify the monitoring, watching the condition beats servicing on a fixed clock. What it requires is instrumentation, a baseline and somebody who can interpret it, which is why it belongs on a handful of assets rather than on all of them. The allocation is also not permanent. An asset that was non-critical becomes critical when the process around it changes, and nothing about the asset itself signals that. Re-reading the allocation once a year, against what the site now does rather than what it did, is a short exercise that catches the assets that quietly changed category.
Questions people ask about maintenance programs
What proportion should be preventive?
There is no correct proportion and published ones assume a site like the one they were measured on. Allocate by consequence and by whether the failure gives warning, then read your own results.
Is run to failure irresponsible?
Not when it is chosen. It becomes irresponsible when the asset has a safety or production consequence, or when nobody has confirmed there is a spare.
Where should a site start?
By writing down which assets are in which category. Most sites discover in that exercise that several critical items are effectively run to failure by accident, and that is usually the most valuable finding of the whole review.