I can see why it would be nice to get more rewards for the roulette for Guildhests but they are very short and typically simple, so while a straight xp increase would help it wouldn't make sense to have them be worth too much individually that way. Maybe something that stacks? Say, each extra one you do within 20 or 30 minutes of the first one gives a % increase in reward. Do 10-12 in a row and end up with something pretty decent. Kind of like, oh what's it called, oh yeah, chain xp for mobs. This chain/stacking buff could be good once per day.