An art blog post suggested new work (paintings, etc.) be roughly divided into 1/3 safe, 1/3 new, and 1/3 risky. https://fineartviews.com/blog/147894/safe-new-and-risky I feel like this also could apply to songwriting especially in a marathon such as 5090 since this resembles my approach. Here are the categories as I interpret them.
Safe > Writing on my most proficient instrument (in my case guitar), using chords, fingerstyle arpeggios, and progressions which I know well. A melody in the sweet spot of my vocal range. Writing in a familiar song structure on subject matter which I know very well.
New (approach/technique, obvisously all songs are new) > Changing it up somewhat, maybe content is in my safe zone but the song is a collaboration. Maybe playing a somewhat familiar chords or melody's but not my most proficient instrument. Maybe I stretch my vocal range a bit and sing in one of my weaker keys.
Risky > Picking elements of the song randomly. A random collaboration. Or playing a much less familiar instrument. Or trying something new or unusual to me on guitar (like a different tuning) or an unusual for me time signature. Or writing lyrics on subject matter that I know little about. Picking random lyrics by using a word generator like Lyricloud to generate a word list and using all of the words on the list. Using the cut-up technique. etc. Using wacky sound effects or unintended preset sound effects for a different purpose like using a Garageband guitar effect on vocals. Chromatic or weird sounding melody or music. Maybe writing something a lot out of character and uncomfortable.
What is your definition of safe, new, and risky songwriting and approximately how often do you venture from safe to new to risky? I'm probably not too far from the 1/3 each split for songs I write. Admittedly most of my keepers started in the safe or new area but there are a few from the risky songwriting zone.