Creating a complex model of a mobile robot

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I'm creating a model of a mobile robot manipulator. I have it in urdf and viewed in rviz with ROS. The model contains two robotics arms, with two robotic hands and a mobile base.

My main doubt is about how to organize or set up the model in gazebo. I mean, it's better to have all the actuated parts in separate models or it's better to have only one model including all the actuated parts?

Of course, I'm talking in terms of maintainability and performance.

Thanks