I have a question regarding the splits for Jill NG+. What are the best settings? All doors or all key items? Because the splits I downloaded from the ressouces have a total of 306 splits (I just renamed them with only numbers). Does it actually matter or the number of splits doesn't change anything?

Just personal preference how many splits you use but you have to make sure the amount of splits match the amount you have ticked in the settings so it's synced up at the end of the run and you get an end time you can save as a pb. If you have door splits enabled, you'd need to reference a run on the boards in the category you're running that's using door splits only to see how many there actually are and then add any key items you have ticked to that number also. Only use door splits if you have the route down and you don't do random backtracking.