Does completely ignoring your SAC scores and scaling and whatever until you actually get your results help things or is it usually detrimental?
Depends why you are looking at your SACs. If you are looking at your SACs with the attitude of every self-depreciation (e.g. "I'm so dumb, i couldn't even get this right) or exaggeration (e.g. woohoo i full marked this sac imma get a 50 with no study this year) it's probably not beneficial as you are either going to make yourself depressed or mark yourself overconfident, both would likely cause you to work less than you need to/should be.
What you should be doing with SACS is looking at them in the aim of self-improvement with a critical eye, trying to identify areas you can improve on to better your results (such as structuring of responses and timing to name a few).
Basically, in my opinion, past SACs shouldn't be used as a window into determining the future based on the past, but rather should be looked at with the aim of using the past to better understand ways to improve in the future (e.g. is there a technique you got wrong/are you badly timing your self...stuff like that).