1st of all it's impossible suit everyone.
2nd of all Since olympiad games are twice in a week (8h event), I believe that deserves a bigger change than Sieges once in two weeks (2h event).
My suggestion would be -3h oly / -1h siege or -2h oly / 0h siege; (It means both events starting same time in different days).
Unfortunately I don't see that "potencial change/help" without big harms. If you push ++hours for these events, you go overnight in europe. if you push --hours it goes overnight for some american countries.
3rd of all 1st.