For instance, Caught Somewhere In Time is the title track to Somewhere In Time. Although it doesn't have the same title, the album title was derived from it. The album called "Somewhere In Time" sounds better than "Caught Somewhere In Time".
As you could read from numerous Harris' interviews, they usually don't target specific name for lyrical concept / theme on the record. They use something they think of as strong title.
Piece Of Mind's first title was Food For Thought. They had this "brain" ideas going on because of McBrain joining the band. In the end they thought that Piece Of Mind sounds better than Food For Thought, and they were right. Still Life has nothing to do with it, and i don't know how the hell did you all think that it says "piece of mind" in the song. It just doesn't have any sense.
Hypothesizing about lyrical metaphors in commentary sections is ok, but face the fact that some albums don't have a title track.
Piece Of Mind - name came from McBrain related jokes (artwork too), songs contain history / psychology / fiction / mythology. No common theme recurring. It's just a bunch of songs.
The X Factor - should have been called Blood On The World's Hands, Harris changed the title. 10th album, and he thought that "X Factor" sounds cool. Therefore, no title track. If it were called BOTWH, that would be the title track. In reality, it has none.
Virtual XI - again a play with album number, with all the hype going with VR in 1998 the title sounded "relevant". There is one track, the opener, that has lyrical theme that would fit the album track. Again, that song is called "Futureal". All other songs aren't related to the subject at all, they're quite diverse. If they wanted Futureal to be title track, they would either called the album Futureal or rename the song to Virtual XI (with a variation ala CSIT/SIT). Songs don't need to have title words in their lyrics. Again, Still Life doesn't have those words in it's lyrics.
AMOLAD - a title that sounds good and sums the theme behind all the songs on the album. Someone said that FTGGOG is the title track. Nonsense. Most of them could be "title" tracks because the damned title was made so it reflects those songs! For me personally, the title reflects Brighter Than A Thousand Suns more than others, because that song talks about life creating ultimate device for it's death.
As in commentary, we sometimes project our personal experiences and opinions and the way we see things, but as in commentary that has some songs too well "documented", backed up by band interviews, leaving little to no room for our fan speculation, here we have pure statements and logic from band members about album titles and how they've came to that. If you want me to remind you, Harris will always pick one of the tracks for title, if he thinks that the name is strong enough. What does in common have NPFTD's title track to the rest of the album? Nothing. We have songs about WW2 bombers, Jimmy Reptile, S&M sex, social commentary, submarine warfare, Russia...But it's title track because it is. Simple as that.