Although it is not necessary to check your cervix in order to practice FAM effectively, I urge you to learn how to do so. At a minimum, I think you should practice checking in the days leading up to and just past ovulation, for the first few cycles that you’re learning the method. Once you recognize how your cervical position reflects your fertility, you will always be able to use it as a cross check whenever you find the slightest ambiguity in your other two fertility signs.
The bottom line is that complete familiarity with the changes in your cervix will greatly increase the confidence with which you observe your fertility and overall gynecological health. And since it only takes seconds a day to check, my attitude is that for those few relevant days per cycle, you should just do it!
A distinct but closely related question is whether those women using FAM for contracption should ever check their cervical fluid at the cervical tip. The short answer is that it isn’t necessary to do so, although if you want to be even more conservative than the FAM rules require, or if you simply want to know your cervical fluid status ahead of time, it certainly couldn’t hurt (Remember that the cervical fluid you normally check at the vaginal opening might have taken several hours to trickle down from the cervical tip). Finally, checking this way may provide some couples with more time for unprotected sex.