I tend to work similarly to some of the previous posters, in that I use a combination. EVERY bit of movement in the script has a text description, generally in-line or opposite, if it is complex (with an assigned number I can drop in the script). That said, I generally manage musicals, and so often times (although this applies to many plays as well) the director has very specific "pictures" or "moments" in which actors' positions (especially the ensemble) are important for sight lines, lighting, safety, etc. At any given moment like that, I generally use a diagram on the opposite page so that it is easy to see when a given performer has forgotten his/her position in that moment.
Additionally, in large musical numbers, in which I'm working off the score rather than the libretto, I use a diagram with performers (abbreviations), arrows (indicating movement), and a number, which I can place easily in the score to indicate when it happens (there is generally less space to write in the score). I find this is also a bit faster (for me) than trying to write out the directions—I simply have my picture, draw an arrow with endpoint, and assign it a number. Of course, I adapt to changing situations, and use whatever seems (to me) to make the most sense at a given moment. The above is just my general practice. ;-)
- P