I am doing single muscle group workouts also with very high volume for most. I also followup with an intense 15 minute HIIT session. But I admit this will knock me out for an hour or two on many days and require I take a nap or just veg on the couch and read and rest etc.
Monday: Chest (4 exercises, 6-8 sets each), HIIT
Tuesday: Back (6 exercises, 4-8 sets each), HIIT
Wed: Cardio (45 minutes with an embedded HIIT cycle), Abs (4 exercixes 3-6 sets)
Thurs: Legs (6 exercises, 4-8 sets each), HIIT
Fri: Arms (6 exercises, 8-12 sets each), HIIT
Sat: rest (sometimes extra cardio day)
Sun: rest