How to Split the 500 Freestyle

Hi, everyone! I'm going to be focusing on middle-distance for at least the rest of the year. Splitting is one of the first areas I'm looking at to improve. During my first attempt at writing out some ideal splits for a 500, I realized I don't know exactly how much a time an average dive subtracts. Is it 2 seconds? 3? More? Less? These are 50 splits from my 500 freestyle PB, a 5:24.50: 29.11 31.33 32.37 32.49 32.95 33.03 33.74 33.50 33.59 32.39 To me, it appears there are three important time additions: 1.) at the 100, adding 1 second per 50, 2.) at the 200, adding half a second per 50, and 3.) at the 300, adding 3/4 of a second per 50. From this, I have two big questions: 1.) should I have gone easier on the first 100? 2.) should those four 33.xx splits in the back half switch places with the 31 and 32.xx splits from the first half, opening the possibility that a completed 500 in this alternate timeline might have more 31.xx splits in the back half, and thus, a faster time? What does everyone think? I apologize if my second question was needlessly complex. I suppose I meant to ask: should I have gone easier on the first half?