Ten minutes, head to toe.
Drift fires a flash every half second and keeps firing as you move, so one pass covers a shin without a hundred separate button presses.
Half a second a flash.
A shin takes roughly forty flashes to cover. Pressed one at a time that is a minute of thumb work per leg before you have touched anything else. Drift turns the same coverage into one slow pass.
The single-flash mode is still there for the face and the bikini line, where you want to place each pulse deliberately. Drift is for the large areas, which is where the time goes.
A session you will actually run.
A whole-body session is about ten minutes start to finish. Ten minutes is the difference between starting and finishing.
Two or three sessions a week for the first three weeks is the front-loaded part, then it drops to one a week. Thirty minutes of your week, at the start, and less after that.