More than three times a week would be ideal, but I've decided I only get to be mad at myself if I go fewer than three times.
I've also decided I should bring my gym bag with me even when I think I am not going that evening - a couple of times I've had things planned, and then they fell through at the last minute, and I couldn't go to the gym, either. So, lesson learned.
I figured out why my deadlifts were so easy last night. It was because I forgot I went up to 30 pounds of plates a couple of weeks ago, and only put on 20. *sigh*