You have a greater potential for more Law tomes than Centurio seals over the same span of time, or at the very least the flow of Law is a lot more reliable than Centurio. You can spam your roulette for Law back-to-back all you want with your role being the limiting factor in how quickly you get queues (and I guess hoping you get a halfway decent group). Your ability to spam hunts depends on respawn timers and your ability to reach the target on time to obtain full credit. At least on my server there are often huge gaps between batches of hunts (and targets often being pulled "early") so even considering DPS queue times I tended to get tomes faster than seals.
