Military press is a great movement. I personally would only use it as an assistance movement on the non-531 press day. But it's great if someone wants it as a 531 movement.
The complaint for beginners has been "not enough volume", even tho they could get it from assistance work. But most beginners want to begin putting mass and strength on quickly and compound movements trump anything in that department.
For intermediate lifters - I would do what I do above and mix up the non-531 movements for that day between a weighted exercise and bodyweight (squat or back raise / DB bench press or dips / Rows or Chin ups) each week to keep it interesting.
For advanced, I would switch up grips, stances, range of motion, etc. to continue making progress and setting PR's in each type of lift (close grip bench, sumo DL, box squats, etc.) For example - stay w/ the sumo DL until you fail the cycle, then switch to conventional and then back again. I wouldn't recommend the advanced stuff until a person has a good 2+ yrs of solid powerlifting under their belts.