As (potential) speakers, we have a number of ways to track CFPs through the year - Joind.In, CallingAllPapers, Twitter Feeds and various other websites and sources.
However, as a rule these rely on the conference organisers submitting to the source you use, or tracking all the different sources. This probably results in us missing CFPs - having been speaking to fellow speakers at PHPUK this year, I certainly know I've missed a bunch of CFPs that I could have submitted to, but didn't know about them (particularly ones outside the #phpc)
As a second 'problem', I know I lose track of which CFPs I have and haven't submitted to (particularly if the conference doesn't use something like OpenCFP), and I know other speakers have similar problems...