Dungeons are reliant on days at times, as they are limited. Fighting 200 brown troops, or completing a number of explore runs, can be done immediately without a wait for another day or replenishing resource, like Dungeon attempts. While it may take more physical play time to do the new task, there shouldn’t be a gate that means you cannot complete it through normal play for a period of days or resets.
Once again, if that isn’t the case and some tasks that don’t adhere to this are found, please let me know.