Texture Atlases - When to and when not to

I have been watching mobile optimization videos for my game and they seem to preach using texture atlases to batch and lower draw calls as much as possible. They end up having 2048/1024 atlases with 10+ models so their scene is practically low single digit draw calls. But the main concern I have is wouldn’t that mean every single model would be drawing from a 2048 texture atlas, therefore adding heavier computation? So I would imagine you would rather use a single texture for more frequent models instead of creating an atlas for this very reason. So that raises my question, am I approaching this with the correct logic where batches should not always be the #1 priority? And if so, what is a good guideline to follow of when to create them?