Getting a random faerie quest at Neopets can happen every few days, multiple times a day or you could go for weeks without getting one. That's why they are called 'random quests'. I have been extremely lucky to have gotten a few Space Faerie quests as well as the Battle Faerie. If you are trying to level up a pet or add to their battle abilities then quests are a great way to go but each faerie has different rewards so you need to know what the potential outcome is before you start looking for the item that they are seeking.