The later cycles are used to challenge and refine the results of the earlier cycles. In most of its forms it also tends to be qualitative, and participative. Some would say that neither of these is strictly necessary. Some insist, strongly, on high participation as a necessary feature. Some have defined publication of results as a defining characteristic.
Action research is also critically reflective.
They refine the questions they are asking and the methods they are using and the understanding and subsequent action plans they are developing. Action research commonly proceeds like this. The researcher, again often involving clients as co-researchers, plans the first or next step. This is then carried out. Researchers meet to recollect and critique their experience.