The code doesn't really require anything about voltage drop but 5% overall is the recommendation in the fine print note.
(3% for feeders and 2% beyond that feeder). If you are going from the main panel you could really say 5% but 3% is not bad.
You also should take into account what the normal load would be.
The multiwire probably gives you the biggest bang for the buck and it is still considered one circuit in article 225.
