Prep Book vs Real Test

I’m using the Barron’s book for SAT Math 2. I took the test in November and got a 730 but I’m retaking the test in December. What’s weird is that the Barron’s book is supposedly harder than the real thing by a stretch. I’ve been taking practice tests all week and I haven’t gotten below a 770. I’m even listening to music and I’m finishing with around ten minutes left. It’s weird but also kind of irritating that I can’t even break 750 on the real Test. Any thoughts if I can get an 800 on the real one this time around?
Just a PS. Only this week my practice test scores have been really high. Before the November test, I used the Barron’s book and consistently scored in the 650s. Between that test and the beginning of this week, I haven’t done anything related to test prep. First test on Monday, I somehow get a 770 lol. I really don’t even know what I’m asking. Just thought I’d share this.