My daughter took it twice (Oct and Nov 2015), with very minimal preparation despite my parental tantrums. The second score was significantly higher than the first.
@GoatMama I think familiarity with the test definitely helps. My kid only took it once but did a practice test at a local testing place (they offered a saturday morning simulation test) and I think it does help. Even the PSAT is somewhat of a run through for the SAT.
^agree
We were told to take it as many times as is necessary to get a decent score (whatever you are looking for). My DS took it last spring for practice (with virtually no preparation) and did pretty mediocre, and he took it last weekend and I am waiting to see the scores before registering again in December. (He has a conflict on the November test date.) Even if he does well enough on this test, I may have him take it again in December with no pressure, on the off chance he does better.
My question is, if need be could he take it on the Jan 7 date and still have scores reported to schools whose applications are due January 15. Does anyone know? I would think so since it’s all the same system, but I wouldn’t want to register for the additional test only to have it be too late to count. Fingers crossed that he (and everyone else who took it) did okay last weekend so we can put that piece behind us 
My daughter took the SSAT for the first time last weekend. I would like to be done with it, but I expect that no matter how well she does (the math has been a problem for her continually, so I’m not expecting a stellar average), I (and she) will think she could do better, so why not try. I expect almost certainly I will register her for the December test, but I’ll have her work through the math section of the Kaplan book I bought (she worked through all of two Princeton Review books before the test). I think taking the test two times is enough for us! I don’t want her working on SSAT stuff over the winter break. It would be better to leave the time for last-minute applications, I think.
@CTMom21 Yes, you DS can take the SSAT on January 7 and the scores will be reported to schools prior to the application due date. Application deadlines vary by school, but even the schools with the earliest deadline (Jan 15) will receive the January SSAT scores on time.
We are waiting for the results from the weekend. DH and I decided that DD can retake the test in Jan if the scores aren’t good enough for the schools she wants to apply to. Her first choice, though, is a reasonable percentile requirement so I am hoping this first test will be okay. She came out of the test feeling like she did well.
@makp715, can I ask what you consider “a reasonable percentile”?
I got it confused - I went to double check before posting and it actually doesn’t list an SSAT percentile (that I could find in a quick check) just the acceptance rate with is more than 50%.