In some cases, such as certain addiction clinics, the patients are required (by law, if I remember correctly) to visit the clinic, at least for some sessions.

First, are we talking about what _is_ or what _should be_?

Second, what is the business logic behind the choice of Date versus Time to represent data (a data point or a segment) in the timeline? And is that logic consistent with the original design, and therefore with how the data have been collected?

There is more, of course. Lots more, some touched upon in the article and comments.