Gmat prep score vs Actual score - False sense of confidence?

Repetition of practise questions is definitely going to create a false sense of confidence and pride. Remember, the Quant on the real deal is no where close to what you might have practised all along. There is no clear procedure to minimize as many surprises on the real deal. Verbal can quickly adapt and bombard you with questions exactly with those you wouldn't be comfortable with, like the method of reasoning, parallel reasoning, flaw in the reasoning and evaluate the argument type of questions on CR or really long and complicated sentence constructs in SC or RC. Even the best performance you can put on the real deal will get you in the range of +/- 40 from your best practise scores.

All you can do is to focus on your weaknesses. Both quant and verbal are equally important. Try to keep quant at above 48 and reach verbal above 40 and you'll achieve your dream score quite easily.