This is not true. There are 3 ways to satisfy periodic confirmation: 1) set a Followee, 2) vote manually on any proposal, or 3) click the button in the NNS dApp that asks you to confirm your Followees. All you have to do is any one of these actions within 6 months. Every time you do it, the 6 month timer resets.
Votes do not cancel out. All you need is for your Followees to reach consensus as described above.