Greetings,
playing Night Market from beginning i noticed people become feed up after not whole 2 weeks, and this event is predicted for 4-5 weeks. When reach 10k favor then peiple go only for another trial keys hunting. I would suggest in next Night Market make sopecific market event bars, that then be trade for purple and gold upgrading materials, for tri-potions, for some new furnitures, part of new leads and even some new mounts. Of course all in calculated value. With this, people who want grind materilas will keep market alive, those who have enough materials will skip.
Also good idea will be increase Nm instance to for example 36-48 people.