Never. Even if I photograph a place or person or thing I have photographed many times for many years, I am photographing in a different time and condition.
Yep, I agree. When you feel like you are repeating yourself and are unhappy, it's time to take a break and reset. For three years, I have taken photos of the front of a same laundry place in my neighborhood (but of course, these aren't the only photos I make). Effectively the same photos, but I find new ways to frame and the light is always so different. It's a a good exercise that shows me that you can never make the same photo and there is always a reason for re-photographing things if you are not satisfied and they are rephotographable. Photography is either fun or it isn't. Your attitude is either good or bad. You don't questions these things when you are happy doing your photography and have a good attitude towards photography.