Don't try to make it 20 minutes; try to make it good! If you make it good and it ends up being 20 minutes, fine. But if you try for a timeframe, you'll put in filler, and 20 minutes is a long time to sit thru filler on a so-so story.
I am working with a few friends for vocals. This is going to take awhile because I am trying to make it 20 minutes long. This will be complete animation and will have complete voices.
(Disclaimer: This is just a sketch and I might not use this but its just a start)
Don't try to make it 20 minutes; try to make it good! If you make it good and it ends up being 20 minutes, fine. But if you try for a timeframe, you'll put in filler, and 20 minutes is a long time to sit thru filler on a so-so story.