That seems like "CYA" advice from the residency application coordinator. Telling EVERYONE to apply to 50 is asinine; there are surely highly competitive people in your class who do not need anything near that amount, but I suppose that gives them something to fall back on where they can say "I told you so" or whatever if someone fails to match. But people think you're crazy if you apply to many more than 20 in peds.
If you want to be safe, then you could apply to 25-30 with a good range of community programs, but as soon as you get anywhere in the ballpark of 10-15 interviews you're going to be fine. I will echo the advice of the above poster that you should touch base with your actual PD and see what they have to say, as they are likely in a better spot to comment than this general residency application coordinator.