Yes, I did multiple shoulder checks, so the mirror wouldn't have helped with me moving in the lane. I was already in the lane and even far left in the lane at this point to enter the about to start bike lane between the turn lane and lanes that went straight. The only thing a mirror would have done was let me know sooner that I had a fast paced lane changing truck coming up my rear, maybe giving me some time to move out of its path, but maybe not.

Generally I don't think i need a mirror to change lanes, I feel much safer with shoulder checks. A mirror would let me know if something is approaching me quickly from behind that I didn't know about when NOT changing lanes and therefor not doing a shoulder check.