I read that graph differently where doing the work + more/extra/nothing is your 8h day. And so if you do the work + any of these it will amount to 8h. If you do nothing, you’ll still be stuck at the office anyway because if you do the work and leave early you’ll be asked to do more since you have leftover time. You won’t get to spend that time on your family.
If you're working from home and getting your job done to the satisfaction of your employer in six hours, I think you can do what you like with the extra two hours. You may need to be available to your coworkers, but the rest is up to you.
