This also documents that the task was done. Helpful if its on another todo list which is currently not at hand. Also helps preventing adding it as new todo since it was already done.
I most definitely used to have a "to-done" list, completely separate from any to-do list. I think it helped me to get a better sense of how long things actually took and gave me an opportunity to focus on my accomplishments, rather than just my failures.
I think it helped me to get a better sense of how long things actually took
I think I need to pay attention to this to improve the dread I feel before starting certain tasks. If I know I only have to withstand it for 5 minutes, I'd be more likely to do it.
Another benefit to this is if your task list is set up in such a way that you can tell when the task was completed. I use a bullet journal with a new list for each week. If I want to know when I took my car to the mechanic or the last time my house was vacuumed, it's easy for me to flip back and look.
I tried picking up bullet journals, but it never stuck. I do love the concept though. I usually throw my to-do lists away once done, but I can see the value in referencing back.