Question on power reserve of portugieser automatic

Hello

I acquired a preowned portugieser automatic ref. 500704 recently. I noticed
that the power reserve is only up to 5.5 days instead of the advertised 7
days? Does anyone have this issue? I seem to recall vaguely that this could be
partially due to the watch being set to "accurate" mode to favour accuracy
over the amount of power reserve. Can anyone validate this? It is keeping an
accuracy of around +6 sec in average for the first 5 days, and starts to slow
down around the 4th day after a full winding.

An average deviation of +6 seconds/day is within specs and not a concern to
me. However, the power reserve should be able to reach the full 7 days - there
is no "accurate mode". This is the latest version of IWC's 7-day automatic,
utilizing ceramic and twin barrels to help improve accuracy and reliability.
Have you tried hand-winding it to see if it will reach a full 7 days power
reserve? If it will not wind to 7 days, then possibly the reserve indicator is
not working correctly. A complete service would certainly rectify this and you
would then have a 2 year warranty on the work done. You may also choose to
address that at a later date as long as the watch is keeping time within
specs.