Summer Update 2021 brought two new hunting grounds in Issavi, the Ruins of Nuur and the Salt Caves. Each cave has two variations of a mythological creature: Girtablilu Warrior and Venerable Girtablilu in the Ruins of Nuur, Bashmu and Juvenile Bashmu in the Salt Caves.
They don't have a fixed respawn, meaning it's not the same creature that always spawns in the spawn spot. After many hunts in these two places, I found out roughly their proportions: 70% Girtablilu Warrior and 30% Venerable Girtablilu, 40% Bashmu and 60% Juvenile Bashmu.
However, hunting in these places I found myself in situations that were very rare in other places with dynamic spawns (mostly in Oramond). Many times a pull consisted almost exclusively of the same variation, even of the less common one. That is, during a hunt in Salt Caves is very common to have a pull with mostly Juveniles Bashmus, followed by another with pretty much only Bashmus, and so on. Of course sometimes they are mixed, but my feeling is that these pulls happen very often.
With this in mind, how exactly does the dynamic spawn in these caves work? Is it just a random chance based on the estimates I found after many hunts for each spawn spot? Is there any intricate mechanic behind these two places?