Oh man, that is the best feeling! I used a smaller knife for years because that's just what I had, and switching up to a bigger one felt like a total game changer. It covers so much more area with each pass, you just fly through the work. Especially on a big flat ceiling, it makes all the difference. I'm glad you found that out, it saves your arms and your time.
That's true for so many tools. People stick with what's familiar even when it makes the job harder. Getting the right sized tool for the task just removes a ton of pointless friction.