What are the Enderman spawn conditions, and ways to improve farm efficiency?

I’m trying to build a super-efficient Enderman farm. In the end, I know the basics for their spawn mechanics (e.g. the light level below 7, and no transparent blocks/half slabs). Is there any way to increase spawning? This is less for practicality than for interest and the desire to produce ludicrous rates of exp and drops.

Solution 1:

Since 1.13:

• Build as low as possible - 1 block above void. No blocks (any whatsoever!) above the spawning level within its chunk. This means each iteration the spawn algorithm ceases search for more spawn places, so new spawns will happen sooner.
• Frame your spawning platform with a 5 blocks wide extension of non-spawnable space, e.g. leaves. This helps the pack spawning algorithm find viable locations and increases the spawn rates near the edges of the platform.
• No other viable spawn spaces within 128 blocks from the player.

Besides that, obvious essential: spawn platform of spawnable blocks (full blocks, or top slabs/upside down stairs etc if you have some reason to make these), light below 7, at least 3 blocks of air (which is moot since you need 255 blocks of air for max spawn rates), means of disposing of the endermen fast in order to keep the number below mob cap, protecting the player area from endermen spawns and teleporting, minimum 24 and maximum 128 blocks distance from the player, and other trivialities.

An example farm utilizing these concepts is Gnembon's EnderMini