The COREsim preferences allow you to set default values to use in your simulations when no value has been specified in your model to ensure consistent results across the project team.
Duration - when simulating behavior, CORE uses the duration attribute for each function to specify the execution time for that function. In the event that a function's duration is unspecified, this default duration will be used.
Iterations - controls the number of iterations to use for any iteration construct that either does not have a domain set defined or for which the domain set does not have the iteration count attribute set.