I think it is always a good idea to keep a record of what you learned.
Since I rarely ever met any foreigners in Oita, I picked up new words from movies. (I can still recite every line from "Casablanca". The whole two hours of it.) I often regreted not bringing a record of the new words I learned from the TIME magazine so I would know what they sounded like. I didn't know the pronounciation to words like "deficit" "fiscal" or "per se" for many years until I heard them spoken in movies. (I often ignored pronounciation keys in dictionaries.) We didn't have CNN in those days and I think kids today have an easier time of it.