I usually discount statements regarding differences between Bishops, Knights, and Rooks, but there is one strange effect I've noticed that seems statistically significant. Bishops sometimes outnumber the other sides during weekday mornings and perhaps afternoons (US Pacific Time) and then are usually fairly significantly outnumbered, often by Rooks, sometimes both Knights and Rooks, in the US Pacific Time evenings. This means that when I log on in the early afternoon the Bishops may have a surplus of fields, from the actions of the "horde" Bishops on during the day, but the tide quickly turns as time goes into the evening and Bishops get outnumbered and, understandably, loose fields. So during the prime time for me to be on, US Pacific evening, I, as a Bishop, am usually trying to defend against significantly superior numbers. Sometimes that gets old, but then it was probably old for Knights and Rooks earlier in the day when Bishops outnumbered them.
The effect seems pretty prevalent yet I am at a loss to explain why it would be so. Do European players preferentially chose to be Bishops thereby increasing Bishop numbers in evening European time?