A few years ago I was in London with my son. We went for a walk with my Hasselblad. My son was 5 at the time. I didn’t know (or had forgotten) what film I had in my camera. I don’t always label the back and rely on memory. So that day I assumed that I had colour film loaded. Well I think I wanted it to be because my son had a red balloon and I wanted to take a photo with him holding it in the street. Because I was unsure I overexposed by 2 stops just in case. Film has a lot of latitude. And it will work whether the film is rated at 400 or 100. So I think I exposed it at 100 ISO in case I had Ektar 100 loaded.
This was one of those times when I thought “Gosh I wish I had colour film loaded in the camera!”