Is there any specific way the splits need to be set up during the run?

Splits are personal, but for the standard Super Mario Bros. the split is every time the new level is loaded. I do it every-time the black screen shows because I'm too used to it. Ultimately its up to you.

thanks! just wanted to know as I'm starting to work on runs.

No worries, glad people are still running this game as well as me!