For a once a month shooter, I would guess the average score to be around 50-65 depending upon natural skill. If you really want to grow and shoot better, try and go more often and ask questions of shooters that are doing well. When I go shooting and see beginners or intermediates struggling, I always stop and watch and offer advice. The biggest thing to improving your shooting is to remember to follow the shot. Alot of shooters point and shoot at where the clay is instead of where it is going to be. You want your point of aim to mirror the course of the clay and when it finally catches up to it to keep going. Depending upon the angle of the shot, you wanna shoot just in front of it or a few feet if the angle is extreme. Do that and you will be shooting in the 60-70 range even if you only shoot once a month.
It matters not how strait the gate, How charged with punishments the scroll, I am the master of my fate: I am the captain of my soul.