mathematically it depends on your current grades. for example, someone with a 3.99 is not going to improve much with one more A, but someone with a .2 will probably improve a lot.
I was just about to ask this same question when I saw your post. Good to know. By this same token, would I be able to take a few university courses *after* I've obtained a degree from a different institution and have them count toward me LSDAS GPA? I would think not, but then why would courses taken as a high school student count toward your GPA if those credits never transferred to your degree granting institution either?