Have you ever heard the adage that if you really want to understand something, you should try teaching it? That definitely was true when I started teaching lessons in the local music store after I finished college.
When you write, you'll find that you're not only creating useful content that your audience can learn from. You're also learning from yourself. So write as you work. It'll make you better at whatever you do. Whether you publish to a blog or keep it to yourself.
A mentor gave me this advice a long time ago, and I wish I'd listened. She observed how much I was learning as I raced through a multitude of projects large and small. And she suggested I start writing down what I was learning -- the mistakes, the best practices -- because I would find it valuable in the future. Whether considering speaking gigs, mentoring younger professionals, or drawing on those lessons for myself, I would be glad I'd taken the time out of my busy days to write it down.
Unfortunately, for years, I rarely if ever took her advice. So take my advice and don't let another day of lessons learned slip through that busy brain!
If you're not a super excited about the act of writing in the traditional sense, try starting a bullet journal. Part planner, part to-do list, part diary, this approach is perfect for the person who wants to log important stuff for posterity but doesn't want to focus on perfect prose.