That’s a fair question. But imagine building a Lego castle without instructions. You might run out of the cool blue pieces halfway through.
A timesheet is your instruction booklet. It shows you where you’re spending your attention bricks. If you’re spending three hours staring at a spreadsheet when you hate spreadsheets, you’ll see it instantly.
It’s like looking in a mirror for your schedule. Sure, it’s a little weird at first, but you learn a lot about your own habits.