When a quest is being verified, the next quest requirement should be displayed.
My latest game addition is Dragon Awaken, and to give it a good try out in the initial stages I played for a few hours to start. The first quest was easy to complete (maybe a little too easy), but while the screenshot was being verified it appears that I overshot the next quest requirements (also quite heavily on the easy side, even for a casual gamer) by quite a margin (which may lead to it being rejected).
Had the requirement been shown on submission of the previous quest then this situation would not have occured
Obviously this is less of a problem with games that have more than one server (Dragon Awaken falls into this category), as you can restart on the same account and get an 'earlier' screenshot, but had it been a 'single server' game then the issue could have been critical to progression on the quests.