After the moment you wake up after a workout day how much actual significant muscle growth occurs in the 24 hours ahead?
Or are rest days to prevent over training and full restoration of strength?
Growth occurs during sleep time not while your muscles are awake and working to keep you walking around.
If you can gain 200 grams of muscle spread all over your body in one week thats 200÷7=28 grams each time you sleep.
This also depends on how often you train and how much working volume you do, both frequency and bolume are key for muscle growth. The more the better as long as you start small and slowly increase both over time.