Square-Enix you didn't think this through (alt leveling)

[Durandil]

I only do guildhests on my healer class. I've done several multiple times, and EXP was gained from them every time, I'm not sure what you're getting at with "they don't reset"

You only get the "first time completion" bonus once.

The first time you do them, you get approximately 8x - 10x more experience.

Doing them more than once is a waste of time, you get really poor experience per hour in comparison to other options.