No disrespect intended: but IRL I allways downshift when I am braking (RFB Manual shift car) as I see no need to lift off the brakes for a downshift and use engine braking and wheel brakes simultaneously also

Maybe I am not understanding you correctly?

SD.
mm maybe it has some benefit like faster reactions

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)
It all depends on the user though and what feels comfortable and this thread definately proves that, so up yours driving instructor man dude.