Most of us never give much thought to how to best take notes. We've been taking notes since we were in primary school and some of us stopped along the way but if you're in complex sales you've continued or restarted notetaking simply because someone on the team asked you for your notes on an account. Just as in school, you settled into a familiar or easy notetaking style. When I started as an SE, I thought about how best to take notes that are useful and concise.
When you're new to a topic, you don't know what's important and what's not, so you end up writing everything, not knowing what you might need in the future. In the process, you spend your attention writing or typing everything that was said, rather than understanding what's being said and mentally preparing your response. That is not the most effective notetaking style, but, understandably, you'd adopt this if you're just getting started. It's important to move to a style where you're mentally separating the wheat from the chaff and just note down what's important to remember later. The chaff here doesn't represent just the unimportant stuff but also points that are easy to remember or figure out later.
Once you've led enough customer calls, you'll begin to see patterns. If you compile these patterns (such as objections, signs showing a lack of understanding of the product or lack of belief in the value delivered, etc) and a list of potential responses for each, it could help you think on your feet about how to respond, while your hands are busy taking notes. In the process, you will take better call notes.