I gave you a downvote, since I'm sure that this theory is simply wrong and might be misleading for unexperienced players.
New mechanism of monsters' spawn were implemented with Oramond with 10.50 update. You can notice that in WOE there is a spawn of stronger monsters like Demon/Juggernaut/Hellhound and they appear alternately with a certain % chance. The same is with Crustacea Gigantica among the sunken area. To trigger it's spawn you have to kill Abbysal Calamary. Bosses like Mahatheb, The Mean Masher, The Manhunter, Burster, Dreadful Disruptor work exactly the same with very small % of chance. Midnight Panther was implemented into the game in 8.70 version. Nobody knew this mechanism that time, it wasn't exist. ;) + it is well known that Midnight Panther resp takes about 3-4 days. If your theory were correct, then it could be possible to trigger it's spawn few times per day.