The post-residency training is still training. For people like surgeons whose baseline residencies are already very long, without getting into the medical field pushing for fellowship post-residency, any extra time is often a bigger investment than it seems.

Also, "intensive" training can be fine as catch up, but (if I had to guess) probably depends on users having some baseline understanding and ability with the machines. A 40yo who never touched one like will feel pretty wonky at the controls and a 1-3 month course likely wont fully fix that. Also, again, comfort needs to be there; you cant just use a machine to do surgery if youre not super comfortable with your mastery of it.