I think that there are just too many variables to make it a scientific absolute. One thing to note is that just under-developing will simply give you an under-exposed image. You should probably over-expose at the time of shooting to compensate.
I tend to cut by a third and have had some success. Sadly, without developing it twice (once normally and once pulling it) I'll never really know what difference it made. I routinely shoot Washi-Z at 200. Over-exposing by 1 stop then under-developing by 1/3.
One thing's for sure though. If you're using a developer that has very short dev times for the film you're using, then it can make it a bit dicey. I never had much success with Rodinal although many others swear by it. The film stock can also be challenging as some film doesn't respond well to pulling.
This is well worth a watch.
View: https://www.youtube.com/watch?v=OdpfRqDDZyw