Is it better to use Mesh Colliders on Mass Projects or Box Colliders?

Pretty much what it says. I have a huge scene and I’m wondering if it saves any if I use box & capsule colliders as opposed to mesh colliders?
When I import a model into my scene I usually just have it generate colliders to save time but maybe that is not the best thing to do?

Any thoughts on this?

I would stick with basic colliders such as the box collider. Mesh collision is expensive and can often have the same results as a box. But, if you are needing a more accurate solution, go with something more complex like the mesh.

You can do either what ChefZweegie suggested, or if you want more accurate results at a fraction of the cost of a mesh collider, consider compound/complex colliders. This video by 3D Buzz does a great job of explaining how you could do this; but basically you parent together multiple empty gameobjects and apply the primitive collider (box, capsule, sphere etc) that you need to each empty from the Component > Physics menu.