I duo Einherjar with another fellow. Einherjar does have a 6 man minimum if you're going to stay more than 10 minutes, but you can clear all Tier 3 chambers in under 10 minutes with two players. Use a Blue Mage or Black Mage set up for AoE damage and a healer.

We do Tier 3 Einherjar as BLM + WHM -> Use Tear / Wing to enter Odin solo on SMN -> repeat.

It averages out to about 2.5k Ampuoles a day.