As an all-day/everyday player..
I won't be doing the poll this event as one important voice is missing: those who were able to complete the event only by use of gems.
With all the possible time I had to baby-sit the game I considered this event (as said way back in the earlier pages of forum) really lacking spawn rates!
OT spawned about every 4th day doing all the collections (not useful at all)
IH not bad but collections being twice per day was not getting you anywhere in the collection!
So.. was only left to push/speedup/gem the Mines to get something! After a couple days of play figured the event was programmed to do so, as spawning frequencies did not change. The cost was not much each time.. but times were many! My opinion after years of play.. is this was the first event planned that way.. and NOT appreciated.