The blue time series is the average view duration across all of my videos by day whereas the orange series is the number of views across all of my videos by day. The range of dates is January 1st until today.
In looking at the graph of average view duration, I was initially surprised at how little it fluctuates over time. The average video view on my channel has a duration of 3:18, but there's not much day-to-day variation. It is possible the law of large numbers has something to say about this.
Then again, I am still a little surprised that high demand days (likely nights before exams) do not also correspond with a noticeable change in viewing behavior -- either shorter attention because frantic students are stumbling upon my videos searching for specific morsels of information, or longer attention because dedicated students are absorbing as much as they can. Maybe the frantic/dedicated effects cancel each other out.