All of these models are idealized. Actual conflicts usually do not follow a linear path. Rather, they evolve in fits and starts, alternatively experiencing progress and setbacks toward resolution. The lack of linear progress helps to give the conflict a sense of intractability . Escalation may resume after temporary stalemate or negotiation. Escalation and de-escalation may alternate. Negotiations may take place in the absence of a stalemate. However, these models are still useful, because most conflicts pass through similar stages at least once in their history.