In principle, different ways of deciding should be applied to different types of decisions.
Deciding how things should be — planning — is well-suited to a flat decision-making structure; that is, where several decision makers are equal and all fully participate. Some call this consensus decision making. As a rule, the longer and wider the reach of the plan, the broader and flatter the planning structure should be.
Deciding how to implement plans — doing — is better suited to hierarchical decision-making structure; that is, roles and responsibilities are stacked upon each other. There is a chain of command and accountability up and down the ladder. As a rule, the more expeditious and short-lived a decision is, the better it is to delegate it to an individual within a hierarchy.
Practical Tip: For each decision, first decide the type of decision: Is it more of a planning decision or more of an implementation-type decision? Will it have long-term, broad impact or short-term, local impact? Apply a decision-making method appropriate to the nature of the decision. Every group member need not decide small, implementation details. Long-term planning and high-level policy should not be in the hands of just a powerful few.