I watched a few videos about how to right a PS and an adcom was saying that 5300 characters is kind of long, and he likes to see around 4000-4200 characters. At the end of the day, the quality of content and writing is far more important than character count, but you are leaving some space to advocate for yourself on the table!
Mine came out to 5299 characters after careful editing and review by me and 3 other people. Go figure.