Totally upvoting this For starters a simple timer would suffice that keeps tracking how long the editor is focused.
And it's really more than a gimmick. Invoices and similar things were already mentioned, But even before that it could be very useful to improve my creative to see how much time I spent on something, It just is more ojective.
I can see if there are areas where I need to put training in to get faster. Or if I simply am at a point where I should start finishing because I'm just gonna ruin things if I continue and so on.