I don't think I can even measure this. I have ideas constantly - form someone asking me a question at work, my kids, family, tv, movies, etc. I have more ideas than time to write.
From the time I actually sit down to write on one of my ideas to publish it all depends on the subject. Poetry can take a few minutes to a couple hours. Depending on emotion or if there is a specific subject.
Articles may take an hour or several days depending on research needed and editing needed.
On average probably 3 hours for me though.