Time limit render in viewport

There is a time limit for final render, but not for render in viewport. I am convinced, that setting 0.25 sec. is more intuitive then for e.g. 1024 samples. In my opinion time limit for viewport would be helpful addition for those who prefer intuitive set up over quality check (I know how fast I click and need to rotate viewport, but have no idea how fast chosen number of samples will be rendered, so always need to check time vs. quality ratio). After setting up time limit, if quality will be not good, time limit can be always increased .