I’ve figured out why it’s so easy for me to think up new compositions but difficult for me to actually write them down: one can intuitively think up songs; in fact, this is how it’s usually done (Fi might play a role too, but it’s a minor one). However, writing them down is a strictly introverted sensory activity… and on the MBTI, Si is the least preferred of the functions by the INTJ type.
But I need to go through the work if my music is to become real.