Given that this is Lange, there must be a sensible reason, and I bet I’ll feel super dumb when it’s explained. So, why is Monday at the 12 o’clock position on the Day of the Week dial?
You can ask the same question as to why Dec is at the 12 o'clock position. Many people count Monday as the first day of the week even though Sunday is traditionally considered the first. Chalk it up to a more secular society.
Because it's the first day of the week. However, the monthly dial defies that logic. Maybe it's just German humour.
Since there are 12 months, and 12 hours on a standard dial, it makes sense placing the 12th month at 12 o’clock. Guessing it must have been a purely aesthetic call to place Monday at 12 o’clock, though this isn’t consistent with that spot displaying the last element of its series (or are there calendars/cultures where Monday is viewed as the “last” day of the week?) Oh, Lange… with your renowned German sense of humor… you!
German humour? Other than their football team at the Euros, I can't think of another German joke I always assumed Lange was just following ISO 8601. And informally, this: http://chartsbin.com/view/41671