Being a "longtrack enthusiast" I never managed to do a really long song by myself yet (with one exception). I'm talking about a running time of 10+ minutes. At 50/90 there are so much songs to make but so few time for doing this - above all a long one!
On the only album from Anderson, Bruford, Wakeman & Howe (all members of the longtrack gods YES) there is a piece called "Quartet" with four lovely and lighthearted love songs merged together. And I find it interesting to see four songs AND a longtrack originating at the same time!
So this is the challenge: Write four songs that belong together in some way (mood, story, musical form, timbres of instruments...) in order to make a longtrack (which can be as long as you want). The reward will be four new songs on your list!
tag each song as "quartet".