When and when not to use VBOs

Hey

I feel like I’m asking questions in excess at this point, so sorry in advance, but:

When drawing dynamic entities, like models loaded from an external file with animations, is it still best to create a VBO every frame?? I would have thought the overhead to be greater than the overhead for immediate rendering.

What if I’m just rendering a simple cube which moves quickly around the scene? That would involve creating a VBO almost every frame just for 24 vertices. It just doesn’t seem worth it.

Performance wise, what should I use and when?