Absolutely! Although I've changed my technique, I always adjust the pH at the end of mixing my witches brew. I also let it sit for about 10 minutes and check and adjust again...as, on occasion the pH will want to jump back up.
Throughout the first 90% of my grow, I added cal/mag, then pH'ed, then all the other nutrients. Adjusted pH again. Then for some reason, or because I read it from two different sources...I began adding cal/mag LAST, then pHing at the end. Don't know if it made a difference, but I used LESS pH Down using the latter method.