Writing things down help commit it to memory.
With people using email and computers more we are writing things down less and less, the younger generation's hand writing is suffering from that too and it is known that when we write things down the brain has a better chance of remembering it. Something about writing it seems to work better.
Writing thoughts will also help you with your thoughts, it can help organize your thoughts before you verbalize it and give you a chance to think about it , add to it later or reorganize it.
As a thought hits your mind write it down !