Is there any circumstances that would require a Magento developer to use Mage::getResourceModel(), apart from when using collections?
I have been developing for a while in Magento now and have yet to come across a circumstance where I need to use Mage::getResourceModel() on its own.
When you’re using a model/resource model pair that doesn’t fall into the standard CRUD pattern, and you want to directly call a public method of the resource model.
A few examples off this in the code base (off the top of my head)