Tips for getting Monopolized?

Me and a few people are going to attempt getting Monopolized and I was wondering if there are any tips we should know before going in. Also I have a question. Is there anyway to stop the game from going to last checkpoint when one of us dies?

you could watch some speedruns just to see if you can use any of their techniques to save some valuable time. per mission, i do believe its your best time on a mission at any time youve played that counts toward the 3 hours. so it doesnt have to be under 3 hours in a concurrent playthrough as far as im aware. you could always play through it all then return to a mission you had poor time on. if that makes sense.

To answer your question, no there is no way to stop that from happening. Halo 2 intentionally reverts you to last checkpoint in co-op when one of you dies to prevent players from “bunny-hopping” from one enemy to another.