I have listened to a few people explaining why taking the time to write helps you think more clearly.
The first point was about presentation slides where we write bullet points, and we don’t have to put any meat around it. By stating it, it has to be true and accepted. It is not precise and there seems to be less critical thinking when it is in bullet form. If you have to write full sentences about your point, you will be presenting some evidence and arguments for it.
There is also a benefit into writing things down. It frees your brain from thinking about it in a foggy way. Once written you can see where you have holes or lack of understanding and can focus on these items, one after another instead of trying to hold them all in your memory at the same time and forgetting some of them. For some, it will also relieve the anxiety of thinking about what you need to get done and how. The process is started, and you can focus on the next step. One step at a time.
The other point that is very important to me was about reviewing your work. Your draft is a quick writing exercise about everything you can think of. It is a brain dump and is probably not organised. You need to review to make it something you are happy or proud of. What I learned was about the different reviews that you should do and that the different angles to have for each review. You should first review for yourself, to be happy with your work and feel that it reflects who you are. Then review it for the people that are going to read it or listen to you presenting it. What do others need from this? You should also do a review for the critics, the one that will tear this apart. What can you explain more clearly?
From that first draft that is probably too long and too verbose about many distracting points, you need to make it clear and concise. Take the time to remove everything that is not really needed to make the point. When in doubt, take it out.
Getting others to review it, even if they are not professional writers can be very helpful. You should ask them if there are sentences or words that are confusing to them. It is important to make it clear and an external perspective on that can be very enlightening.
You should ask them when their minds are starting to wonder when reading your work. If it is not interesting enough to keep their focus, you may have to change the pace of that section.
You can also ask the reviewer what is the 10% that absolutely needs to stay in, no matter what happens to the rest. What is the most important in what you wrote. You can also ask the opposite, what is the 10% or 20% that they would remove.
The fact that all this work will take time to be completed is helpful because you will rethink about it many times and may realize what is missing or what does not really add to it. Sleeping on it is going to help you be more complete.
After going through this process many times, you will start to see the benefits in everything else you do because your mind will be focused on the quality of what you do.