Master/Worker applications

Folks,
I hope I am posting this question in the right area. I have the following doubt.
I am trying to work on parallel Master/Worker applications. In general, how common/un-common is it for the workers to do different amount of work? Is it ok to generalize that most applications that use this paradigm of programming, involve uniform division of labor across all the worker processes?

Thanks

I think if i m correct you are talkin abt the threaded application ? If yes then you can use multi threading concept in your model

Well, I am actually using MPI. I want to create a bunch of worker processes, the master deals with the workers using MPI calls, the workers work on their own contribution and this may or may not involve communication with other worker processes. At the end of a time-step, the workers report back their results to the master. And this goes on a bunch of times, till the exit condition is reached.
I have found a few applications that rely on uniform distribution of work, whereas, one application that I have come across, deliberately divide the work in a non-uniform manner. I want to know if the majority of the applications rely on a uniform distribution.