"but I've seen other actors do a signature song and still make an effort."
But I don't think Popular is her signature song. If she is using it as her signature song, she needs to stop and use one of the songs from Smash, maybe "Just Keep Moving The Line" "Don't Forget Me" or "Let Me Be Your Star" Personally I think she is kick ass on "Just Keep Moving The Line" but if she's going to be like Judy Garland and be singing her signature songs 40 years from now in concerts, she probably should go with "Don't Forget Me" because it will be less wear and tear on her voice in 40 years.
If anyone ever tells you that you put too much Parmesan cheese on your pasta, stop talking to them. You don't need that kind of negativity in your life.