You can do it without but aa tends to sting a bit. Judging by your background, I don't think your no stranger to pain. Some argue it prevents necrosis at the injection site, but if that were the case my bis would be gone!
I always back fill 5 iu bw before drawing the AA reconned igf as I feel it gets every single molecule of igh out of the pin thus pushing it deeper into the site sir...