Good article, I couldn't agree more! Some things regarding dates and calendars cannot (easily) be caught in formulae, take for example:

1. Weeknumbering around newyear. Some don't want a week 53 and sure don't want January 1st to be part of week 53 of the last year

2. Working days: is a specific date a working day or a non-working day?

3. Rare, but I now some cases: for example invoice dates should always fall on a working day. What if we invoice on a Sunday? Move it to the next working day

4. Quarter / Period based on a 4-4-5 week schedule

Things like these I always solve using a calendar table. Seems more logic to the customer as well!

René