Typically, Live Parts™ takes around 5 minutes to generate a steady state object for a given set of model constraints. However, for larger model sizes (i.e. dimensions), Live Parts can take up to 15 minutes or more to reach steady state. There are a number of additional factors that affect the length of time required to generate a steady state object in Live Parts, including but not limited to model size, cell size, gravity wave activity, and change in forces (or their magnitude).
Note: the longer you allow Live Parts to run for a given set of model constraints, the more likely it is that the object generated has reached a steady state.
Refer to this article to learn more about how Live Parts works.