The descent from lunar orbit to landing was broken into three phases, and each of these phases had a specific computer program associated with it. Here’s the way it worked on all six lunar landings:

The descent began with the braking phase — the first and longest phase. It was flown entirely automatically by the computer (Program 63). Its goal was to slow the spacecraft from about 3,800 miles/hour to about 700 miles/hour, and to decrease the LM’s altitude from about 50,000 feet to 7,000 feet.
The approach phase began when the LM was about 7,000 feet in altitude and about 2 miles from the landing site. The computer was still doing all the flying (Program 64), but the crew could now see the landing site and offer adjustments to the computer.
The landing phase began around 500 - 700 feet in altitude. The Commander flipped a switch next to his left thumb, causing the computer to switch to Program 66. The computer was now in what was known as attitude hold. The Commander selected the spot where he wanted to land, and used his controls to tell the computer where to go. The computer was also responsible for keeping the LM upright. The landing phase ends with the LM on the lunar surface. //

Here are the times (in minutes and seconds) that each of the missions spent in the landing phase:

Apollo 11: 2:23

Apollo 12: 1:44

Apollo 14: 2:01

Apollo 15: 1:16

Apollo 16: 1:00

Apollo 17: 1:08

Apollo 11 had by far the longest landing phase — almost 2 and a half minutes. That’s how long it took Armstrong to find a suitable landing spot and guide the computer toward it.

At the other extreme was Apollo 16 — when it entered the landing phase, a suitable landing spot was right there and it took John Young only a minute to guide the computer through the last few hundred feet and onto the lunar surface.

All of these missions went through the same phases — they differed only in how long each phase lasted.

As far as Armstrong being the one to fly the LM, that was also the plan, and again, it was the Commander who guided the LM during the landing phase on all six lunar landing missions. The job of the LMP (Lunar Module Pilot) was to provide crucial support during the landing, monitoring systems and calling out numbers throughout the landing phase. If you listen to the audio of any of the lunar landings, the voice you hear calling out numbers is the LMP.