how to besiege a castle (100% historically accurate)

The average medieval castle siege involved many months of both sides waiting for the other side to give up. Why didn’t they just swarm the walls and launch the heaviest rocks they could find at the Don Juan? 1) The Peace and Truth of God, Chivalric Codes, and the Just War Clause dictated when war was to take place and under what kind of circumstances. War was not to be waged on holy days, civilians were not be harmed, prisoners were not be mistreated or tortured, surrenders were to be accepted, and peaceful resolutions were to be sought over violence when possible. These were Christians concepts and about half of Europeans were practicing Christian during the Medieval Era. They cared about the faith, so these rules were followed regularly. 2) Medieval armies were much smaller than armies of the modern era. Armies were made up of knights and soldiers that were trained from a young age. It was a profession that few were naturally gifted for. Putting an army in high causality battles was risky