My question is: What would the right thing to do?, taking things less
intense giving more room in my estimations?, raising this concern with
I have no intentions of talking about other peers, I feel that
wouldn't be professional. But I don't want either to work 20-30%
harder with nothing in return.
There's no such thing as "optimal" across different people, organizations, and industries. Optimal for you means one thing. Optimal for someone else is likely to be different. However, you can choose a course of action once you decide your goal.
If your goal is to work only to the extent that you are directly and immediately rewarded, then you should experiment. Slack off, and see if your review/compensation suffers. If it does, then ramp up the intensity of your work. If your review doesn't suffer, then slack off more until it does. Eventually, you'll reach an "optimal" point where more work isn't compensated the way you would like, so you can stop working any harder.
If on the other hand your idea of "optimal" includes self-satisfaction, learning for the future, working hard to make the day pass quickly, or just enjoying your work, then your actions may well be different.
First decide what you are looking for from your work, then let your actions be guided by that understanding.