I only do one body part per day and I changed it about 3 month ago I use mainly free weights I am 40 6'1" and weigh about 246lbs
BF?
You need to check your diet. Make sure you are also ingesting ample amount of protein. You have to assist your muscles protein synthesis especially when you are consistently working the muscles.
Here is the steps in order from most important:
1. Diet
2. Sleep
3. Routine
4. Workout
Why?
Without diet, your sleep is usually off, your routine is pointless and your workouts are useless.
Diet in check, sleep (recovery) in Check, routine in check, and workout... In check
Make sure you aren't just prancing around the gym aimlessly working out.
One of the biggest things I learned, was what the machine does for my body. How my muscle reacts to the push or pull eccentric etc...
Then I was able to properly lift.
Routine, instead of one muscle a day, group them.
Back Biceps
Chest triceps
Legs abs
Etc..
Grouping will help you much better
Work in the 8-12 rep range for 4 sets each routine. MAX WEIGHT for that rep range. Don't be afraid to near failure.
If you aren't pumping enough, superset workouts.
You can workout long or you can workout hard. But you can't do both.
Make your time count!