Seems as good an explanation as any to me Ron, although I wonder whether it's just us Europeans and the South Americans who see 45 minutes and immediately instinctively think of a football half?!

Remember too that at the time it wasn't just the 45 Dato that had the 45 minute register for the chrono, half the Carrera range was 45s and there were Autavia and Camaro 45s too - it just looks more obvious on that second execution Carrera 45 Dato because they ditched the perpetual seconds register for somewhere to put the date where it was less likely to be obscured by hands.

Heuer certainly produced stopwatches that were intended for timing halves:

As well as some more obscure sports - waterskiing anyone?

Anyone got any candidates for any other activity where 45 minutes is such a natural division?