Honestly, if you keep getting, say, 70+% of these tests, you are sure you can pass the test. However, keep taking the same set of tests several times might not be helpful, because even you get 100% for every test, it might only because you have worked them out for 100 times, and you already memerized the answers.
Thus, what I suggest is, try to read the materials carefully, understand the concepts, and take the tests not more than 5. In fact, what Bert and Kathy suggested for HF
EJB mock is to take the mock only once after you are ready. This is the case that could reflect your real situation.
Nick
SCJP 1.2, OCP 9i DBA, SCWCD 1.3, SCJP 1.4 (SAI), SCJD 1.4, SCWCD 1.4 (Beta), ICED (IBM 287, IBM 484, IBM 486), SCMAD 1.0 (Beta), SCBCD 1.3, ICSD (IBM 288), ICDBA (IBM 700, IBM 701), SCDJWS, ICSD (IBM 348), OCP 10g DBA (Beta), SCJP 5.0 (Beta), SCJA 1.0 (Beta), MCP(70-270), SCBCD 5.0 (Beta), SCJP 6.0, SCEA for JEE5 (in progress)