What made you pick letters over numbers in the first place? I did something close to this last year when my Sunday planning was eating up half my morning, and the fix was not the letters themselves but dropping the idea that every day needs its own label. My setup got faster once I stopped tracking days as separate units and just grouped them into blocks, like A week for admin stuff and B week for deep work. The other thing that saved me time was cutting my list down to three things max before I even started. Most people spend 40 minutes setting up because they are really just avoiding the actual work. Try it for two weeks and you will see the letter thing is less about the system and more about not overthinking it.