I allways had manuscript books while making albums. Say, for example, "The Ascent" on RIE, It had to be written down first.The chords were changing all the time. Some parts I used to try and keep in my head. I was a doer so Playing it with the band was allways the first option. Sometime I wrote at home first, like the music for what became " DWTIME". Usually the music could be kept just in my head. I did score the middle section of Vienna. I some times have a look at it now. There are drawings all over it!
It was half score half map. For the string part in the middle I just wrote down Strs at the point they should come in. ie Last beat of the bar. C - Dmin . And then just improvise the part. My parts were allways a mixture of Very Definite Note by Note or try things until I got what I wanted. Loose ish so to speak. I still work like that now. Hope this helps,