You find that Business Rule Framework is very flexible and can be adapted to fit the most extreme complex decision making. However, there is always a limit as it cannot make all decisions a human can.
Humans are emotional beings, making decisions that seem not logical. Those illogical decisions cannot be made by BRF+.
Imagine you have several routes to visit family. You have the fastest route, shortest route and most ecological route. The decision on making the type of route depends on many factors that is based on logic. For example, road blocks, traffic jams, weather conditions or time of day can influence the decision. By default you would imagine that everyone would select the fastest route. Still, even on a normal day you can select a different route that is not based on any logic. Maybe this time you just take the pretty route because you get bored with always driving the same way to your destination. This is emotional decision, not based on logic. Such a decision making process cannot be replicated within BRF+.
Business Rule Framework can guide you from A to B as soon as you have selected the type of route. You can process all influencing factors that could support the most logical decision. The more data you supply to the BRF+ function the more likely the most logical route is selected. But the result is always pointing to the decision that would make the most sense given the circumstances.
You find that it will be extremely rare that business decisions are of an emotional and illogical nature. That is why your challenge is to challenge the business requirements to get very specific details how decisions are made. Just not accept that you sometimes need to go left when in apparently same circumstances need to a different direction. When a specific person makes a specific decision then dive inside the thought process up to the moment that a binary choice is made. Then try to describe how this core binary decision is made and then work your way back to how this impacts the business process involved.
When you use BRF+ for complex decision making then it is useful to build a prototype as soon as you receive the business requirements. Then use this prototype to challenge these business requirement up to the moment that all binary decisions are identified and approved in the prototype. You might need a lot of information to make decisions, but that is the point of this exercise. You are eliminating potential reasons to fail user acceptance testing at the end of the deployment process.