Avi:
The tzaddik whose advice comes via Ruach Hakodesh can freely provide it even without being asked. After all, he knows whatever he needs to know anyway. In practice, one is free to believe that his rebbe possesses Ruach Hakodesh (I am not engaging in the debate of whether or not Ruach Hakodesh exists in our times). But one cannot be certain that this is the modus operandi at any specific time and place. So when seeking such advice and guidance, the rebbe must be presented with a carefully deliberated question. If the situation is medical, how can one seek such advice from the rebbe, who was presumably never in medical school and is totally without training? The obligation is either to come prepared with the needed information, or for the rebbe to inquire of the experts until he is comfortable that he has the full picture.
Quite many poskim delve deeply into subject matter before giving advice or paskening a shailoh. Reb Moshe Feinstein inquired in detail before concluding about anything that entered the realm of science. Reb Shlomo Zalman Auerbach studied for hundreds of hours before emerging as the prime posek for shailos concerning electricity on Shabbos.
The strength of a psak is directly dependent on the strength and accuracy of the shailoh asked.