Leif Segerstam writes lots of symphonies. Not as in Mozart wrote a lot of symphonies, not even in the category of Haydn and Hovhaness wrote a lot of symphonies, Segerstam is in a different category. Right now he is somewhere in the 270s for his symphonies. Most of them are intended to be performed without a conductor. Each part has timings and when they should play in time with other musicians. Each section even has directions on who should begin and end it. His symphonies have inspired me to start sketching out one of my own for winds, piano and tympani. We'll see if anything comes of it.
As I said in my first post his music is very free. If you click the link below and look through his catalogue you will find bunch of PDF files of some of his works.
Below I've included video of his Symphony No. 212 which was written for Gustavo Dudamel. The work was divided into two sections i'm assuming to meet the file size requirements of YT. Go listen to it. Enjoy it.