Incense was the clock before the clock

Before mechanical clocks, a stick of incense was a unit of time. Not metaphorically — incense clocks with measured trails were used to time examinations, meditation periods and night watches.

That history is worth keeping in mind when you light one. A stick burns for a bounded period, and the period is the point. You are not perfuming a room; you are marking a duration.

Practically, this makes incense the easiest practice to keep. One stick is short enough that there is no excuse, and long enough that something happens in it.