There are two very different views about when FFs are fun. Some say its fun when a fort is filled on both sides. I can understand that, but its not my view. I like FFs when its a close win (or lose), an achievement, surprising developments etc. I remember very exciting FF with 10 people on both sides, and I had boring FFs that were filled.
sure. but with multis, it almost every time means each side will defend their fort(s), and there's almost no attackers. or, the attackers dig a lot of forts at the same time and focus on one, while defenders are spread all over which results in one walkover and a couple defenses against nobody. chances for a fun battle are second to none with multis. at least in my experience...
That said, 'prime time' FFs are good, but there should be FFs at very different hours, so everyone has the chance to be online at one or two battles a week.
and that's what a good agreement should bring. reasonable parties will be ale to reach one, as someone said above.