RE: leucine on non training days?
This may help you:
Leucine is unique in its ability to stimulate skeletal muscle protein synthesis and has a far greater stimulatory effect on protein synthesis (10 fold ) than any other amino acid. Leucine is what's known as a "limiting nutrient" - meaning that you must have enough L-Leucine in proportion to other amino acids in order for your body to make use of what you eat. Supplementing with upwards of 2gms of L-leucine per meal has been shown avoid this rate limiting effect, which is more pronounced in older populations.
Personally, I take Leucine on waking, pre & post workout and before bed.