From the late 1970s his compositions expanded in length to such a degree that the second string quartet can last for up to five and a half hours. My whole generation was hung up on the 20 to 25 minute piece. It was our clock. We all got to know it, and how to handle it. Up to one hour you think about form, but after an hour and a half it's scale.
Form is easy - just the division of things into parts.
But scale is another matter. You have to have control of the piece - it requires a heightened kind of concentration. Nine one-movement compositions by Feldman last for over one and a half hours each. This came about from a request from Bunita Marcus, for whom it was written, for Feldman to sum up everything he was doing in the very long pieces and to condense that into a smaller piece. Knowing his sense of time, she asked for a ten minute work, knowing that it would probably be twice that length.