look down

i have the same problems. i write a lot of stuff on my own and at the time feel like the material isnt bad. but when i read it over later in the day or week i feel like its too amateur. even stuff i have written over the summer has good content but isnt presented the way i want it to be, it just seems under par of what i want it to be. but then when i read poems and listen to music i feel like some artists have crappy lyrics every now and then too. i want my stuff to sound more professional and am trying to have lots of good techniques and rhymes and all when i write but it cmoes out less appealing then i thought. i also have the question of how long does stuff seem to take other people? is writing a poem/song in 5 minutes average, or does it take people a week of revising? i realize anyone can write something in 5 minutes thats good from time to time but i;m also not sure of how much revising to do or how much time to put in to a poem. there are so many hit songs that people have written in 1 hour and other took them months. the more i revise my stuff, the more i completely change the original prompt, and i end up writing a completely different poem, which isnt bad but i could have just written 2 different poems and came up with 2 instead of 1.