I believe its still mostly 4 day trips as 3 days tend to go senior. Most or all of the time, trying to trip trade from a 4 to 3 day will not happen (due to low reserve coverage - supposedly). Then again, if you are trying to change a 4 day to another 4 day with same days, that also will be denied for some odd reason. Anyway, expect 4 day trips over the weekends if you are junior and holding a line.