I REALLY should not be answering, but...
I took the SAT every year between 7th grade and senior year, except for the year when you take the PSAT.
The big advantages I felt like I had were that the SAT didn't make me even a wee bit nervous by the time it really mattered, and that I was very well-prepped, having studied several years in a row instead of merely cramming for a week or two beforehand, as most kids do. Also, I think I improved at figuring out how to read the questions. I had a better sense of what they were asking and didn't get tripped up easily by tricky phrasings.
I think the practice also gave me something of an advantage when I took the GRE, the standardized test required for grad school, BTW. By that time, I had gotten very good at learning just enough to do really well on standardized tests.
FWIW...
Oh, and by the time I took the PSAT, it was a breeze because I'd already taken the full SAT 4 or 5 times by then. LOL!
