Thanks for getting back! You’re of course right about super-precise timing. I should clarify that this is fMRI, so what I am looking for is what is described in the link I mentioned: I just need roughly precise timing of the experiment (a few ms of drift don’t matter) which PsychoPy should automatically achieve from the builder when all routines are green.
Reading from the CSV log/data file, however, I find a roughly 4s drift accumulating over the 25 minutes time course of the experiment (as calculated from begin and end times of routines, relative to the time of the initial trigger sent to the parallel port that starts the actual experiment).