[Someone WAAAAY more smarter [intentional] than me says this:
"Manage fatigue, don't seek it."
(First one to guess the author gets a spanking - your screen name must be southerngirl, karma, or gymgoddess to participate.)
I'm none of the above but the pen to that phrase belongs to none other than CW in Hybrid Hypertrophy. I prefer a paddle, ridding crop or ruler, but you don't get the honors.
Back to the original question. I vary the days I lift to fatigue based upon my energy and plans for the week. I work odd hours, lately Monday is the day I hit it hard and heavy.
Superset Squats 5 X 5 125 and step ups 5 X 10 w/ 50, standing calf raises 3 X 12 w/25 (my calves are big enough) and Ham curls (whatever you want to call them) 4 X 10 w/60 slow tempo. Dips, bent rows, close grip bench, wide grip bench, L-seat, Lunges, DLs for fun, serratus crunch, and some other ab stuff. This is the day I hit everything I am currently working on and hit it hard and heavy. Then I go run 8.8K.
It's a long day, but I know I will not be near the gym for another 48-72 hours so, I have plenty of time for recovery. Then I go back to the usual split body parts routine usually lighter weights and shorter runs.
I have basically bastardized a couple programs around here to target specific areas. Then the other 3 days I stick to something more normal. I can't say how it is working yet as I have only started this in the last 2 weeks.
Short answer is experiment and see what works for you.