Indeed, @thomasjpfan’s terrific blog post inspired our thinking on this topic. Ultimately, though, we’d rather opt for a workable option that the community is willing to adopt, rather than for the “optimal” naming.
scikit-image has to make a decision relatively soon, so we’re in a similar boat as we were in with SPEC 7: Seeding pseudo-random number generation.
The num or n prefix has also come to make sense to me, personally, to distinguish it from passing around worker objects.