Was feudalism successful?
Well, it lasted quite a long time, so the system must have worked well enough, or it would not have continued so long. I think feudalism was generally practiced in Europe during the medieval era. As a system, it was in some ways an improvement on what had gone before. The manorial system, which developed under feudalism, meant that the land was worked by peasants who were bound to stay on the land they worked on, but they could not be bought or sold like slaves, and some of them became quite wealthy by acquiring more land. Eventually most peasants became free.