I love O Brother Where Art Thou but damn if that movie doesn't have some weird pacing and scene changes.

I think it's because, before the film had released, the Coen Brothers said it was based on The Odyssey. Then afterwards they admitted that they hadn't actually read The Odyssey.

It kind of feels like they got a cliffnotes of the main plot points and tried to cram as many of them in as they could.