Many Paths to Process Improvement
Processes can be improved in a variety of ways:
- Cycle time.
- Lead time.
and probably tons of other dimensions, too. If your process is repeatably two hours faster, rather than a statistical outlier, then you could certainly say your new-and-improved process is 10.5% faster than before, but it may or may not be more 10.5% more efficient.
Speed <> Efficiency
Whether or not your process is actually more efficient depends on how you choose to interpret efficiency and what you want to get out of an optimized process. Consider these examples.
- If your process is 2 hours faster because you've added another person to the team, is that more efficient?
- If your process is 2 hours faster, but has an increased defect rate, is it more efficient?
- If your process is 2 hours faster but requires more fuel per widget produced, is it more efficient?
These aren't trick questions. The answer is just as likely to be yes as it is no, because for most organizations "efficiency" is a buzzword that's really a proxy for something else. In my own experience, it's most often a proxy for value/time or value/cost, but an engine manufacturer might think an improvement in the rate of energy capture is what the process ought to be optimized for.
Unlike some of the hard sciences, efficiency is a less objective term in project management. Therefore, your mileage will vary.