For longer runs such as completing arc1, would segmenting be allowed? Or am I required to finish it in one sitting?

Usually those aren’t allowed. But I can remember reading in the game’s rules that it is allowed for a certain amount of time but now it seems to be gone .

There used to be a break rule because it took more than 12 hours. But now all runners complete 12 hours or less without a break, so the break rule has been eliminated.