Very helpful! This method is often referred to as "creative visualization". It's part of a Zen-type concept that is described in (among others) the "Inner Game" books ("Inner Game of Tennis" is one of my favorite books about MUSIC, period!).
The concept of visualization has helped me as a performer, but more so as a writer. When I "hit the wall" in the composing process, I "put myself in the audience" and imagine listening to the composition, and most of the time the "solution" reveals itself, as if it has existed all along and I was simply overlooking it by focusing too much on the "process" and too little on the music itself.