Unfinished songs seem to be par for the course. But it depends how prolific you are as to whether or not it's important.
When I first stared writing, every note was precious. Every phrase
had to be used as I never knew if there were any more coming. But as I realised the "well of inspiration" might not be as shallow as I thought, some ideas which didn't come together quickly, I realised could be left behind.
I still revisit them every so often and occasionally they pop into my head dragging the "missing" piece with them.
Those are joyful days.
But sometimes I don't think any of my songs will ever be finished, but the law of diminishing returns kicks in.
At some point you just have to say that will do, and leave everything else up to whoever is playing them. Their interpretation will probably be slightly different from the original idea. Even the author, playing the song a year later, will probably play it slightly differently.
Mihkay