The writer on the website, Never Mind the Bricolage, (whose name escapes me and my record-keeping at the moment) is discussing the notion that two of Radiohead's albums, written ten years apart, can actually be woven together to form a musically coherent album. At one point he has this to say:
I think it was someone like John Mellencamp who said in a Rolling Stone interview years ago that all musicians only had three or four songs. What he meant was, if you listen to most of your favourite artists, their musical palette is probably quite narrow in terms of things like chord sequences, particular rhythms and characteristic sounds. It's why songs have a familiar feel to them even though they are new. It even goes a bit wider than that, maybe you've been to a U2 concert where they have woven someone else's song into their own and it fits melodically etc. Pop music is quite simple really, two or three chords, built around a beat add lyrics---the artfulness is not simply in the structure but what is done within that structure.
When he's talking about musicians, of course, he's talking about the popular scene; more serious composers might consider that they had a couple more than three or four songs in them, or even three or four themes. We'd hope so.
Nevertheless, when you listen to any Mahler symphony, or any other of his works, the Mahler trademarks turn up all the time. That's perhaps slightly different to the personality of the composer being inherent in their music: Mozart always sounds like Mozart, as does Beethoven, but they don't tend to use Mozart or Beethoven ''trademarks' in the way Mahler does. He might be an extreme example, and I might be waffling here (it has been known to happen). Thinking about my own music, I don't in general find there are recognizable connections between one piece and another - but perhaps it takes an outsider's ear to hear them?
Totally unrelated to this, it's interesting that when I was younger I generally wrote words like 'recognisable' with a 'z' instead of an 's': recognizable. For some reason I seem to have slipped quite unconsciously into the 's' approach as the years have gone on. There now, wasn't that interesting?