The placebo effect refers exclusively to medical treatment if I'm not entirely mistaken, and this seems to have much broader implications in basically any sort of training.

While the placebo effect is generally defined in a medical context, people rarely throw type errors when you talk about placebos outside of medicine. The Hawthorne Effect is the name that productivity boosts due to observation / novelty / active treatment go by, but it's seen as similar to if not the same as the placebo effect.