The lead article must have been written quite a few years ago, as it makes no mention of Preterism, risen in recent years becoming very common among both postmills and amills. Once Historicists or Futurists, they have morphed into Preterists. It’s hard to find Postmills or Amils nowadays, who do not hold to some form of Preterism.
The variations Postmills and Amills have to do with how they interpret prophecy in relation to time, past (Preterist), present (Historicist), or future (Futurist).
Premills, on the other hand, are Futurists... whether Historic Premill or Dispensational Premill. On the end time tribulation they are pre, mid, or post.
Correction:
The variations Postmills and Amills have, has to do with how they interpret prophecy in relation to time: past (Preterist), present (Historicist), or future (Futurist).