On the different subdial variants, I have often wondered the same thing.

To the best of my knowledge (I'm 30 so wasn't racing sailboats in the 70s and 80s), the red flag has always been the "Preparatory" signal meaning 5 minutes to the start of a race. But depending on the size and number of boats, the race committee could specify a 15 minute, 10 minute or 5 minute countdown starting sequence.

So it would make sense to me that in theory that the Red portion of the subdial should come first b/c
1. In a 5 minute sequence it's correct
2. You will often find yourself re-setting your time at the 5 minute mark to get it exactly perfect

The 10-5-0 w/ white first seems really confusing

I tried to use a mechanical chronograph last summer and it was quickly retired for my digital.