The article suggests that for past events, UTC and this timestamptz would be acceptable as a general rule, but even there it depends on what you will be doing with the data. If you intend to interpret it as a series of local occurrences and try to visualize/summarize that data later, you may be in for a surprise as your user has moved to another timezone and now all the past events are translated to the wrong local hours [0]. For example, your system might end up showing that the user's best time for jogging based on historical data is at 2 in the night.