Match time.

[cookizzz]

As I remember, there was a restriction that match time can only be changed 12 or 24 hours before the match. This can still makes the other side very inconvenient, but at least they have some time to react.

Edit:
Slightly out of topic. I often arrange some immediate friendly matches in next 3 minutes. Actually I understand that this may also cause convenience to opponent. Opponent manager only has about 1 minute to refuse the friendly match. Even though their player condition was not harmed, the manager cannot manage the team for 10 to 15 minutes during the match. If that manager only have this time slot in a day to make some changes, they will not be able to do so. So even though I personally I like this friendly feature, I don't defense if others complain about it.