The Deductive-Nomological model, strictly speaking, certainly seems ideal but is untenable.  This is ideal for empiricists arguing from fixed premises but this view hardly seems amenable to novel discoveries and even predictions.  D-N does have a robust explanatory scope and power of causal laws such as the law of conservation. This model doesn’t have any explanatory power for other laws (i.e. the Pauli Exclusion Principle, which prohibits atomic electrons from collapsing in on the nucleus and being propelled away from the nucleus).  The D-N model, if it were to implement the Pauli Exclusion Principle, would have a self-defeating condition in the explanandum or explanans (depending on how the principle is being used). So, the model itself seems inert to the effect that it could never be verified or falsified by its own merit and criteria.  It stands in a privileged explanatory position.

Additionally, the D-N seems incompatible with many models of our universe.  This model assumes that the universe is deterministic.  Its view of causality is more than the Humean notion of effects rooted in habits of association, and rightly so, but it assumes that causality is applicable in every instance of a law.  There are several problems with this in the quantum world.  Quantum calculations are solely based on probabilities.  The vast majority of quantum interpretations are indeterministic (i.e. the traditional Copenhagen, GRW, Popper, transactional, etc.).  Additionally, there are other interpretations that suggest that the quantum world is deterministic (i.e. de Broglie-Bohm and Many Worlds).[1] What this goes to say is that the world may not be completely deterministic but it’s certainly not chaotic either.[2]  This is where I get caught between the efficacy of the I-S model and the D-N-P model.  The D-N-P model makes sense of deterministic and probabilistic explanandums.