Daily Mazes, Bounty Hunters, and Double Delights are week-long events that proceed in a recurring order (Daily Mazes > Bounty Hunters > Double Delights).
When the Daily Mazes event is active, the Arcane Labyrinth refreshes daily instead of 48 hours.
When the Bounty Hunters event is active, the Bounty Board rewards are boosted by an extra 100%. It is beneficial to refresh the bounty board to acquire more relevant rewards. This can include extra Hero Essence or Diamonds. Rare Hero Soulstones and Gold are also useful but dust and diamonds are more scarce especially in the early game and are refreshed for more often. A refresh costs 50 diamonds.
When the Double Delights event is active, the regular AFK rewards of Gold, Hero Experience, and Hero Essence are doubled. This does not include Fast Rewards and saving AFK rewards prior to the event also has no effect.
Hope this helps!
Credits to u/zeedafluff.