I think we can dedicate one whole sticky on that. 
Anyway, let's get back to the thread, shall we?
Let's face it.... optimally the platoon sergeant ought to be the
most experienced person of all in the platoon. If I'm not wrong,
the average age of the PS in a US army platoon is about 28 or 29.
Contrast this to the SAF - we can have pimply-faced 19 year olds as
platoon sergeants.
Heck, in many cases the men end up being older than the PS.

There's nothing much we can do about this. We're a conscript army,
and we don't have the sufficient manpower to allow the situation
where the PS is a highly-experienced soldier in his late twenties
who has seen it all. I guess the only thing we can do is to firm up
the standards for the PS selection process and make sure that not
any green soldier can become a PS.
Inevitably there will be some black sheep, and I've come across
total jerks who think that the stripes on their sleeves entitle
them to respect and fear from the masses. Nothing we can do about
getting rid of jerks in the Army, but at least we can try to
prevent some of them from getting stripes on their sleeves.