It depends on how much you want to get in, the strength of your application and how flexible you are.
More specifically applying to one school drastically reduces the chances of getting in. I'm in Texas and it is not uncommon for folks to apply to 5 or 6 of the 8 programs here in Texas, if not all of them. If you live in the northeast then there are even more. Way out west less so. If you are willing to relocate and have the money to get to interviews and pay fees then the more places you apply the better your chances.
Strength of application is also important. If you are socially akward, do not appear confident, have a 2.0 in undergrad basket weaving, don't really know what a PA does and have no healthcare experience then you are going to have a tough row to hoe. If however, you are confident without being cocky, socially adept, have a 4.0 with a BS in molecular biology and an MBA, have previously been a paramedic and respiratory therapist then things will be much easier for you.
I'm not trying to be a smart-***, but there are a lot of things to consider.
Which school you want to go to, prior and future debt, family commitments, willingness to relocate and your desire to be a PA. It is really hard to tell you more without specifics about your situation.