Trust takes years to build because character needs time to run out of excuses.

Anyone can behave well for a while, especially when things are easy and the cost of good behaviour is low. Time matters because it accumulates situations: the inconvenient favour, the moment of temptation, the disagreement with something at stake. Eventually a person runs out of easy circumstances and you get to see what remains. That is why trust cannot be shortcut.

Rather than deciding about someone quickly, let time and varied situations do the work. Notice how they behave when it costs them something. Speed in trusting is not generosity; it is just skipping the part where you find out.