Ken Schwaber, co-creator of Scrum said: «I estimate that 75% of those organizations using Scrum will not succeed in getting the benefits that they hope for from it… Scrum is a very simple framework within which the «game» of complex product development is played. Scrum exposes every inadequacy or dysfunction within an organization’s product and system development practices. The intention of Scrum is to make them transparent so the organization can fix them. Unfortunately, many organizations change Scrum to accommodate the inadequacies or dysfunctions instead of solving them.»
In order to overcome increasing complexity in organizations several execution models following agile and lean methodologies have evolved, one of them is called Scrumban, a hybrid of Scrum and Kanban.