Yup, everything I've read seems to indicate, "you can never skim too much".
I believe most people try to get a skimmer that is rated for double the tank volume. So, for a 55 gallon, you'd want to go with a skimmer that is rated for at least 125 gallons.
I actually had one of these on my 92 gallon (back when it was a Fish Only with Plastic Rock...oh the humanity), I found it worked well but I had to constantly adjust it to dial it in.
We may run it on the 92 gallon again if we don't get the Sump/Skimmer package we're looking at right away...