Hannes, your IWC is a fantastic watch and a very emotional heirloom in the family. I've just looked at the watch on the net, really very nice.
Modern movements are becoming more and more precise, not only in time accuracy but also in mechanical quality with very tight tolerances. I'm not an expert but I can observe that watches with simpler drives don't need a revision so fast. My 2002 Speedmaster was checked last year and still has a nearly like new amplitude in all positions. The same applies to the not so expensive ETA drives. The manual drive of the Speedmaster Professional is basically from the early 1940s.
But the 2004 Coaxial Broad Arrow had to go for 850€ to a revision last year. The drive is much more modern and complex but obviously much more maintenance intensive as well.
