I've done 2 pilot/4 sector days, 3 pilot/2 sector days and 4 pilot/1 sector days (some 2)
I've been fatigued on all combinations but I can tell you only one usually needs a whole day to recover after...4 Crew ULH.
I don't care about how much time you think is off asleep if you do the math. The reality is that much less sleep is had than mentioned and the body knows when you get home.
FFRATS