Regardless of the statistics, your chances of passing after coming to our CCIE TM practice lab are completely dependent on how well you study the concepts before coming to the Practice Lab. Other than the obvious benefit of being able to practice lab scenarios to reinforce your book studying, one of the biggest benefits to spending time in the Practice Lab is to work with the same equipment you will see in the CCIE TM hands-on exam. Getting over the shock of seeing the equipment before the exam is very helpful.
Cisco recommends a minimum of two days for a couple of reasons.
First, there is a limited amount of practice you can do in one day. Second, the hands-on exam is two days. Its difficult to practice for a two day exam in one day. The average person appears to schedule three to four days of practice time. Also keep in mind that if you buy four days, you get the fifth day for free.