The efficiency of internet filters depends on what you are trying to do on the internet. The fact is that everybody is trying to win. While the Companies providing security are constantly updating their software, the enemies are busy updating theirs also. Filtering software that works this week might not work for updated enemy software in few weeks.
From my experience, the filters are not 100% efficient. For instance, in the process of downloading some technical information from the internet, you must first accept to download an exe file. The problem is that lots of unwanted materials are sometimes hidden within the executable file and will trigger some pop-ups while trying to download the information you actually need. Accepting or the rejection of the invitation from these unwanted pop –ups depends on the moral conduct of the individual. As a Christian the best filtering solution is our own Christian values.