I'm on the No side of things. I think having quarterly breaks or bi-annual breaks will result in "Invasion Week" much like Shark week, where every faction puts in Invasion declarations right after.
Right now its spread out kinda. There were 12 invasions in the last 12 months involving 8 Factions. Only twice did a Faction have back to back months with Invasions taking place [Prime=June+Aug, Mandos=Jan+Feb], and there was a November/December break in Invasions anyway, and September and March were void of them as well. The Most active conflict was OS vs GR which had 4 Invasions last 12 Months, 2 from each.
If something like this were to take place, I'd dig seeing a One Invasion (Attacking) per month, just like a T3 Dominion is once per Month. I'd still expect to see breaks occur naturally, and Factions have historically taken breaks after an invasion anyway. Even if you did 2 months between attacks I doubt we'd see a difference. Just my 2 cents.
*April Geonosis [TU vs Rebels]
*May Telti [OS vs GR]
*June Geonosis [TU vs Rebels]
*July Wayland [Prime vs Mandos]
*July Ord Mirit [OS vs GR]
*August Ziost [Prime vs SSC]
*October Balmorra [OS vs GR]
*October Contruum [OS vs GR]
*January Roche [Mandos vs GR]
*January Lujo [GA vs OS]
*February Alderaan [Mandos vs GR]
*April Togoria [OS vs GR]