Did a short 2 hour test at beastlands.

Results:
- drop rate with alchemist : 4 essence / 100 mobs.
- extract rate without target: 4.5 essence / 100 mobs.
- extract rate with target : 2.5 essence / 100 mobs.

| Time for 100 | Time for 25 red |
----------------+--------------+-----------------+
Grind with alch | 250 mins | 400 mins |
Extract w/o targ| 500 mins | 421 mins |
Extract w/ targe| ---- | 240 mins |

Conclusion:
Even with large error margin, with basic grind
you get maximum amount of essence and by using
extract with target you get maximum of certain type.
Extract without target is useless.

Thoughts?