Once you discover all chests you go to a new map with new chests, so you can't be wasting keys.
The crates contain 5 rewards each so every <36 keys you practically get 30 extra rewards in very reasonable quantities. They are the exact same items as those available from Time To Train so in the end you'd be better off doing Buried Treasure. As an added bonus the skilling and protean crates seem to be a more common reward than during Time To Train.
15-May-2017 21:48:13