Ron_W
1634
IWC does not use COSC but its own parameter of 0 to +7 sec p/day for their inhouse movements, so fast is good. The slower UTC may be affected by rotating the UTC hour ring ? but as long as its stable rate p/day i am okay with it.
For their inhouse Portugieser i am much less flexible but it has run at 1 or 2 sec fast every day now for 8 years or so. remarkable !