I’d never heard of 120% until this thread, but I immediately interpreted it to mean “you’re free to do your self directed 20% work on nights/weekends/your “own time”.”

It actually took me a second to see yours, but I guess you mean more of a “ya you can do whatever you want on fridays as long as you get 100% of work done by Thursday” vibe?

If you use 5 days a week as base and add 1 day for personal work, you're at 120%.

Of course interpreting it as "you need to work 125% for the 4 remaining days" is equally valid.

Or the 16.6666667% policy