[Norfleet]

Wendigo makes a good point: If you're holding Vanjarls for military purposes, the cost effectiveness of using them for a secondary task like researching or bloodhunting is far less important: They're going to sit there anyway, why not put them to use?

The relative virtues of blood hunting as opposed to researching vary depending on one's situation, but bloodhunting is definitely a valid solution for an idling Vanjarl who's on a stakeout for military reasons, rather than economic ones.

However, for a dedicated bloodhunter, scouts are unmatched by anything other than a Mictlan priest, and neither scouts nor Mictlan priests are really strong choices for other uses that would necessitate keeping them around doing otherwise nothing.

While you may have a half dozen to a dozen Vanjarls sitting around waiting for a fire to extinguish, it'll surely take more than that to fuel a strong blood economy, however. They may do a fair job earning their keep as blood hunters in the meantime, but never forget that this is simply busywork, not their primary purpose.