The one-lift-a-day workout was popularized by lifting coach Dan John. This is another great one that saves time and keeps you focused on the one goal for that day.
Sometimes doing 3-4 exercises per body part can be mentally exhausting. If you only have one exercise to do that day, you can attack it with greater ferocity and focus. Since overall volume is low for the day, you can recover faster and increase frequency of training. I have had many clients break PRs on these days. Sets and reps can vary according to goals but here is an example of a program geared primarily towards strength.
Day 1: Barbell Squat: 6 sets x 5 reps
Day 2: Bench Press: 6 sets x 5 reps
Day 3: Weighted Pull-Up: 5 sets x 8 reps
Day 4: Deadlift: 5 sets x 6 reps
Day 5: Dumbbell Shoulder Press: 5 sets x 8 reps
Day 6: Bent-Over Row: 5 sets x 8 reps
Day 7: REST
–Perform at least three warm-up sets ahead of your first working set.