I never understood the purpose of having insane encounters like this, especially when there is no stack function. It doesn't serve much purpose to send yourself insane; technically, you would be better off changing your hunt every few hundred attempts.
Of course, there could be other factors at play, such as certain functions within the source code that impact shiny chance depending on different account conditions, e.g., hours played. TBH, this would be smart to encourage RP purchases, and it wouldn't surprise me if this were the case. But in all honesty it sounds like a skill impairment.