This add-on helps, it has politely reminded me that I should spend only a limited amount of time on some web pages.

I am subtracting 2 stars because the add-on screenshot is different from real behavior, it has a large window with content:
"Add a 5 star rating...;
🙌🏽 Tell your friends and colleagues: ".
That window has pushed the main window to right side and is up to my face, for the past maybe a month. Finally that request managed to push me making a firefox add-on account and publishing this review because I have read that 5* review request for the past month every day, literally every minute (on some web pages).

Overall I appreciate this add-on, thank you.