Jason Summerville in his Run It Up vid says something relative to this, along the lines of: It seems you will find that the players up at odd hours fishing for games are typically pretty great, and if you get in a short handed game in the wee hours of the morning you are more than likely gonna find some sicko(s) just looking for action.
It would seem logical to expect that more common players will be found at more common hours. That when the site is flush with players that there will be more weak players to choose from, and games to pick from. The sheer number of weak players will rise, and not that that indicates a raise in frequency of fish, it simply states, when there are more games and more traffic, there will be more to choose from, and with the increased diversity in the field, it will be more likely to find a table suited to a player's particular strengths, logically. More volume means more opportunity for diversity. I'm guessing the difference in these players that Jason S. refers to have much to do with players that are so strong they are able to adapt to any table, and conditions and fid a way to profit, so in the lesser volume times, it would seem the strength of the most adaptable players will shine...
just my 2 cents