It seems like some people don't understand the use case for week numbers, at least for businesses. They allow the ability for time series comparisons for a work week. Using the calendar date is hopeless because the 21st day of a month could fall on any day of the week.
I want to compare the Monday of the first work week of the year to the Monday of the first work week of last year. That's most helpful when trying to understand sales trends, etc.
The ISO weeks are also big in automotive, especially on projects that span over a number of years. It automatically aligned most activities to have a duration measured in whole weeks. Sure, you can use fractional weeks, but then it gets really messy really quick.
I appreciate the usefulness of using weeks to measure time. But on a side note: less than 10% of time assigned for validation/testing and at the very end of a project is, in my experience, extremely ambitious.
I don't disagree with you. Some of the decisions that went into the ISO standard are real headscratchers for those of us who have been using North American week numbers
I want to compare the Monday of the first work week of the year to the Monday of the first work week of last year. That's most helpful when trying to understand sales trends, etc.