.And that full rudder recovery presents the risk of spin in the opposite direction.
The full rudder thing was about the scenario where at the point of stall, a sharp wing drop occurs. It is widely taught (and I don't know why) that recovery in that situation is to keep ailerons strictly neutral and apply opposite rudder to skid the dropped wing level by causing it to move faster than the other wing and thus generates more lift. The theory (which is BS) being you level the wings while lowering the nose to unstall the wings and you never used any aileron.
The problem with that BS is at the very low speed the aircraft is at the point of normal stall, instant full rudder is guaranteed to flick the aircraft into an incipient spin. Especially if there is a slight delay in lowering the nose.
Certification of aircraft designed in the past 40 years or more (Cessna series etc) require the ailerons to be effective below the stall, whereas aircraft in the old days (pre-war, post war) some had vicious wing drops. Application of opposite aileron exacerbated the wing drop. The classic was the Wirraway single engine trainer where the aircraft could flick inverted in a high speed stall. Hence the general advice when flying those types, not to use instant aileron to level the wings. Instead use only sufficient rudder to prevent a dropped wing from going down further and after the stall is broken by lowering the nose, use ailerons in the normal manner to level the wings. The whole maneouvre, including applying full power to minimise height loss near the ground, should be accomplished normally inside no more than 3-5 seconds.
But from interviewing hundreds of GA pilots over many years, you would be amazed that the vast majority said they had been taught by their flying school instructors to level the wings by rudder only - meaning literally skidding the wings level. Commonly called picking up the wing with rudder. And that is as recent as just a few days ago talking to airline candidates at flying schools that specialise in training cadets for selected airlines.
So whoever is training general aviation flying instructors are pushing old myths..