Each leadership team is different. We can say that there are unique, because we are dealing with people and how these people interact with one another. This human component makes each situation different.
With this stated, there are a few typical problems that leadership teams face. First, with a plurality of leaders, there might be a deadlock in terms of an issue. Even when there is a majority, it might be a slight majority. This can cause conflict. Second, with a team, there always the problem of many points of view of varying insight. This can slow things down considerably. To many views is not always beneficial. This is an important point to keep in mind, because time is money in business in many ways.
In light of this, a mixed structure might be the best option. A leadership team is a good idea, but it might be necessary at times that there be one person who makes the final decision based on all the input.