I play on microlimits and in my experience I did not notice any special differences in the strength of opponents, depending on the time of day. Wash percentage of strong and weak players remains the same, no matter at what time of day you play. The main difference in the number of participants. But I think that this is due to the difference in time zones. In the countries of Eastern Europe, there may be the middle of the day and many players from there play at this time, and most Brazilians, for example, play when they have a day, and we are already late at night.