Is a good song worth anything on its own? Or does it only become worth anything if it is part of an album?
If it's the latter, then obviously songs being individually great means nothing, since an individual song is worthless. The entire album needs to be great, flow and not having a weak track is the most important thing.
I'd imagine for most people though, a song on it's own does mean something. It certainly does for me - I like listening to full albums but to be honest, if the album flows well and is great to listen to as a whole, that's just a bonus. So what if an album doesn't flow well - what if it's just a collection of songs, that don't necessarily have to be listened to together? Is there anything really wrong with that?
So for me, Train Of Thought is a great album, possibly the best DT album, based purely on the quality of the individual songs. In The Name Of God, This Dying Soul, Endless Sacrifice, Honor Thy Father - all are top teir DT songs for me. So even if the album does get a bit heavy going to listen to all in one, I still think it's great.
An album being good as a whole does count for something, but one that is full of great individual songs isn't going to get many points taken off it for not being an album that has to be listened to as a whole.