As noted by a poster:
Immigration's own website will read that a student visa is NOT needed if
you would be in a course of study that is less than 22 hours per week of
classroom OR less than 18 hours per week of "practical" study.
I have done recurrents and initial type ratings now at Flight Safety, the shortest was the recurrent, and that was 3 days of 8 hrs each in a row, so even a recurrent would need a student visa.
Just get a visa, end of story!
If you or someone else is investing the money in a type rating or recurrent then why try and skimp on something as easy as a visa !