I’m find there’s something called “a crystal point”.
I first look at a number and I start out complaining: “How am I going to do it with so few instruments?” “Why does he make these compositional choices? They seem arbitrary.” “Shouldn’t there be a much more different arrangement?”
Then, I’ll go and procrastinate - torrent a little, a book on tape, a book on Kindle.
Then I’ll come back to the chart and maybe look for a starting synth sound, stare at the screen for a few moments ...
Then it lines up ... a sort of ‘crystal point’: suddenly a few colors in my teeny tiny band match an odd choice of the composer - a synth patch work for a figure here - a woodwind choice is just right for the line there - throw away that vocal doubling - add a fill into the gaping hole there with a fill.
This moment usually happens about 1 am. I often stand up and go right to sleep. Colors and choices don’t disappear from memory like pitches and rhythms do (at least for me.)
Occasionally such a crystallizing moment (is that a more apt phrase?) occurs upon first hearing. Receiving an assignment from a performance as opposed to the printed page presents solutions much more quickly. if the emotional journey of the song is clear, and you’ve become familiar with what your present instrumentation can do ... sometimes all the right choices play out in your head as you are listening. The score page becomes an issue of how well you can execute what is already obvious.
The challenge, of course, is when such a moment of crystallization does NOT occur - and you have to move forward anyway. You want to think that only you can recognize which scores were inspired and which ones just got done. But sometimes, it’s all too obvious.