You are asking two different questions in this one thread if I understand the second question properly, I think.
Some people say that God told me such and such and, who knows, maybe he did…but there is no proof for it. Other people will say God told me such and such in prayer, and it sounds more credible. Either way, it can’t be proved one way or another, I suppose.
In regards to your first question, we first need to look at what “wisdom” means in this Biblical context. I learned from one source that it can mean a savoring of the things of God, in an other source, seeing people and things more the way God sees them. It has also been defined as a gift that allows a person to see the purpose or plan of God, which is similar to the former. Another interpretation is the capacity to see things at a deeper level, underlying causes, or showing a high degree of prudential judgment.
When a person asks with persistence and sincerity, God will indeed give liberally, but it is not like a bolt of lightning, happening in an instant. I think I can say that I’ve seen this in my personal life, but I still make lots of stupid errors in judgment. Solomon made a huge one. Sometimes, scripture means something a little different than what we think it ought to mean.
