The "Weekly Challenge" is just a mess. "They" use significant volume of resources without any benefit of return on completion. If one does an adventure, there is always some return of resources, generally commensurate with the difficulty and resource use.
The "Weekly Challenge" needs to be rethought. Perhaps the challenge could be designed to require a player to complete a number of adventures, from a list if desired, and gain extra XP upon completion.
The XP gained from the present situation is good, but the resources used are not replaced, for example, at lever 56, one does not mine saltpeter nor Titanium, but use of these resources is necessary, requiring acquisition from the Trade, which may not be an advantageous thing.
Hubertxiv