FWIW, I accrued 800 of these hours over the course of my required practica in my program (the other 50 were elective during an extra research year). As I said, 500 hours is the minimum for many internship sites in my area, and it is not at all uncommon for applicants to local sites to have more than that.
Whether or not that many hours is "overkill" depends on where you live and the type of specialized sites to which you're applying (some do require more hours). If the OP is applying to prison sites in certain areas of the country, more than 600 hours is required. Just saying that one should be sure to accrue enough hours to be competitive for the sites to which one is planning to apply (perhaps OP will choose only to apply to places with lower stated minimums).
Finally, applying for the match isn't the only reason for accruing therapy hours. My intention wasn't to pad my application (and I don't encourage trying to rack up unnecessary hours simply for that purpose), but to advance my training. I'm grateful for the depth of experience that I had, and I'm a better clinician for it.