I had tremendous difficulties with this task. Firstly, I wasn’t able to observe people as intensely as would be required for later drawing them. It would have amounted to staring at them for prolonged times, and I felt this was socially not acceptable. I did not want to make people feel uncomfortable by staring at them, and I did not want to feel like an offender to social rules.
Then secondly, the minimum amount of time I considered socially ok for observing any particular person was not enough to build up my memory for later drawing. I also tended to feel overwhelmed with visual impression and had a hard time focusing on anything particular because the memory of any observation tended to be wiped out by the subsequent observations.
There was one image I drew from memory, it was that of a young girl riding in the bus, sitting opposite of me. This drawing is in my “moving people” sketchbook. It is better than I had expected as far as the amount of detail that I was able to remember is concerned, but overall it is a rather weak and faint drawing. Maybe drawing from memory might work better if I could draw immediately after having watched someone. For now this is difficult to organize with my fulltime working schedule which keeps me overbusy and exhausted.