Two people, the same forty minutes
Answer it in your head first, then look.
Two people scroll for the same forty minutes on the same evening. One comes away flat and the other comes away fine. On this lesson, what is the difference most likely to be, and it is not willpower?
Where their line for should be by now has been pushed to. The feeling is produced by the gap between that line and where they actually are, so it depends on the standard rather than on the minutes. Somebody whose line has not moved much can look at exactly the same posts and feel nothing at all.