The exercise is then ridiculous for you.

May I ask what your line of work is? this is often a key issue. If your job is not particularly manual and doesn't involve squatting, kneeling or other activities where a lot of knee flexion is required and if you don't need that extra 20 degrees for what you want to do when you are working then it doesn't need to be a big problem.

As an alternative you could always get some more physio if you wanted to work at getting a bit more. But to be honest you can do a lot of things with 110 degrees knee flexion.