Lean Philosophy is focused on the elimination of waste, particular the waste incurred by everyday work. The first and most important part of eliminating this waste is identifying it.
Many persons, whether employed by someone else or self-employed, go about doing work in a haphazard way. We simply try many things and stick to whatever works best for us. The obvious issue with this is that we may not know where we are wasting our efforts - some may not care enough to stop and consider where wastage occurs and others may want to make the effort to consider it but lack the methodology to do so.
Lean methodology posits that wastes can be identified through measurement. For example, we cannot know that we are typing slower than most persons unless we do a typing test to determine our average typing speed.
Conclusion
Businesses need to minimize wastage in order to improve the efficiency of their operations. This can only happen through objectively measuring the value generated and taking intention actions to correct the waste when it is discovered.