Often times, there are questions that could be considered on-topic for several of the Stack Exchange sites. For example, there's some debate whether Is camera flash actually harmful to infants or newborns? should be moved to the Skeptics site. I think my question about the physical limits of sensor ISO would also work on the Physics site, and might get better answers if it were listed there as well. I could probably come up with dozens more examples.
It's arguable which site would be better for these questions, but I think it's clear that there are people on either site which could answer the question well. These two questions are at the margins of what's on topic for the Photography site -- someone who's very skilled with a camera won't necessarily know the answer to either of these. I think it would be worthwhile if these (and other) questions could be cross-posted on multiple sites to increase their exposure and improve the quality of answers.