Dynamic workload management (DWLM) applies the same principles as the workload manager (WLM), such as routing based on a weight system, which establishes a prioritized routing system. The exception is that rather than manually setting a static weight like WLM does, DWLM grants the system the ability to dynamically modify the weights to stay current with the business goals.
If you are using dynamic operations for the cluster, then you set business goals and use policies to define your threshold and setting a static weight is not useful. If you are working in a static environment, then set a static weight.
If you intend to use the automatic mode for dynamic operations, then setting a static WLM weight on any of your dynamic clusters could get in the way of allowing the on demand aspect of the product to function properly.
If you have a cluster that you do not want to be dedicated to the work at hand, then you can create it as a static cluster and define a static WLM weight to it. By doing this you are setting aside a percentage of the cluster for other work.