One element in timezone decisions is that kids should make the trip to school in daylight. But that is futile in Finland. Today's sunrise in Helsinki (very south) is nearly 9 o'clock.
Winter and latitude, not longitude should of course guide the selection.
Dublin today, Nov 30th, marks the start of the 6 week period where
daylight is less than 8 hours, IMHO only wintertime (UTC) makes sense here.
Oddly IST, Irish Standard Time and legal time, is UTC+0100.
Sticking with IST all year round means 10:00 sunrise in late December for
the north-western most parts of the country (Belmullet, for example).