All of my songs are guitar-based, so the length of completion depends. I usually spend about 3 or 4 hours learning how to play the song and the accompanying harmonies. Here's where I start to introduce my original content and alternative arrangement ideas. I spend another 3 or 4 hours programming drums, rehearsing the parts, and maybe recording scratch tracks for my own benefit. The recording process could take me anywhere between 3 and 5 hours, depending on how well I'm on my game that day and how many tracks I need to record. Then I could sit and mix the song forever and never be completely happy with it. Realistically, I might spend 2 hours mixing. So over a few-day spread, I could probably complete a song in 12-15 hours. That's for an average length 5-minute track for me.