One of the most unproductive actions software can take is sometimes out of developer control; the software crashes, possibly taking with it some amount of accomplished work. When using computers there's nothing quite so frustrating as realizing that a considerable amount of thought and labor will have to be re-created from an unknown point of failure.
Almost all software is guilty of instability at one time or another. About three years ago, feedback from Revit customers pressed the point as a high priority -- we needed to focus on resolving bugs and mitigating instability. A reality of the software industry -- and for that matter, the manufacturing industry -- is that products ship with flaws. Sometimes those flaws are known, and in the best judgment of the product leadership, are considered to be minimal drawbacks compared to the compensating value of the same or other new features. Sometimes flaws only become apparent when a product goes into production.
One common measure in the industry of product stability is Mean Time Between Failure (MTBF). When applied to software development (rather than, say, hard drives), the measurement is the mean time between software crashes. Longer times are better, indicating that the software is becoming more stable. I'm happy to report that after several years of concentrating on quality, the Revit product line has been on a favorable trend, culminating most recently in an MTBF of ~132 hours, as illustrated in the chart below. Over about 5 years, that's a rise from about 18 hours when we first focused on crash issues.
With typical patterns of Revit use (about 50% of a working day, on average), that roughly corresponds to 32 business days between crashes. As always, your mileage will vary depending on many factors, including whether you have the latest service packs installed for both Revit and your OS.
Whenever I show this chart, I'm asked about the erratic graph for Revit LT. When we see numbers bounce around like that, it's usually a sign of low reporting -- Revit LT isn't as widely adopted as Revit, so there's less opportunity for statistical "noise" to even out over many more reports.
We're still not satisfied with these improving numbers, and will continue to focus on increasing stability and reducing the effects of new and legacy issues in the Revit platform.