Depends who you ask. I'm sure Shana voters would rise if they found that bunch of guys who spent one month in a Taiwan winter waiting for Rie Kugiyama to appear.
From what I've found, the vote total seems to be higher for rounds 1, 4 and 7 since they have the big matches more often than not.
And I'm going to say another thing - if you want your character to win ISML, you'd better rally support for this year. Because in 2011 things will be very different. Yuri and Angel have very big supporter bases already and have ended the reign of Yui and Yuki in the various niches within Japan. Needless to say, Angel Beats will be a VERY serious challenger to K-ON and co. next year. Throw Sora no Woto and Hanamaru Kindergarten into the mix and you've got a lot of threats.