It depends on why and how you want to include mustard in the rotation. Do you want to use it as green manure? For fertility/weed or pathogen suppression/ erosion control purposes? Simply as another crop because a wheat/rice-monoculture-rotation is not sustainable in the long term?
What farming systems are you speaking about (smallholders or large-scale export-oriented farms...)?
Obviously the answer depends on the context of environment (soil, water, climate), agricultural system and boundary conditions (market access, economic considerations).
The green revolution led to high yields and astronomic benefits for some in these very fertile areas at the cost of eroded and soil, water and destroyed rural livelihoods of many. To increase the complexity of the agroecosystems is a good idea in most cases, being mustard a starting point, but there are many more possibilities to increse rotational diversity (and subsequently the resilience and sustainability).
An article that may be interesting for you:
Article Agroecology and sustainability of agriculture in India: An overview