Era 1 is busy all the time 'cause all you do in era 1 is finding a route which brings most money, and it changes every hour.
you actually have different strategies, and it strongly depends on the scenario. I agree with you for classic (who plays classic?) and to some extent on USA. But for Europe, making money in era 1 is definitely not your main concern (or you want to make money while developping the landmark, which gives you periods of low income where you don't need to be around).
at the end, people that want to win the server will be online a lot even in era 1 (those videos are gold in era 1 !), and others might not need to be around a lot even until era 6.
Personnally, I do prefer "shorter" breaks (10 days is fine, but more would be too much) because I know I cannot play fully on 2 servers, and then if I have to wait for 1 month for my server to restart, it might be too much.