After that the arena game play becomes unhealthy...
That's so ambiguous it hurts. How does one decide it's unhealthy? For you? For me? For goodness' sake, don't try to decide what's fun for me. Or for others. Your opinion is that the arena game play becomes "unhealthy" (wtf is this being used here in this context for, anyways? I feel like I'm reading a cigarrette package or something...) when there are large numbers playing.
Me, for one, over the last 8 years of playing and paying for AH (and AW, WB...) found the funnest days were the ones where there were tons of people on, with fights all over the map. You had HQ raids going, huge pork missions launching from behind the lines trying to stop an advance, multiple CV engagements, formations of buffs and fighters launching to intercept... And some crazy furballs with players from all three sides going at it. Heh, I think my first major upgrade to a pc was because I wanted faster framerates and better detail in AH back shortly after Y2K.
I still find Tuesday to be the most fun day for me, because virtually all of my friends are in one spot, and we're able to play together without limits in a late war setting.
Unhealthy? Meh, maybe in your opinion, but sometimes those kind of things are actually the most fun. You know, fast cars, unsafe sex, a good whiskey...