Yes, please make more instances available in some form of Duty Roulette.

If you want to encourage players to use the roulette more than once per day but don't want players to spam it for bonus farming, spread the once-per-day reward over multiple runs. For example, instead of 50 tomes on the first run per day, it's 40, then 20, 10, 5, 5, and 0 after that. Players are sure to complain if the DR rewards are nerfed, though on the other hand some will complain if it becomes too easy (a valid criticism, value of existing effort shouldn't be diminished), so the first run rewards are kept almost the same.