Reddit mentions of On the Psychology of Military Incompetence

Not really, I think the most important factor is the length and applicability of the training. A WWI British army trained along pre war lines of superior rifle marksmanship would have been waste of time and just led to more dead tommies with even less results.

The thing about mass conscription is it widens the pool of intelligence and experience within a army. I'd suggest reading Dixion's "the Psychology of military incompetence." http://www.amazon.com/Psychology-Military-Incompetence-Norman-Dixon/dp/0712658890

Where he examines a great tradition of Volunteer military who went conscript during WWI/II. The interesting analysis is how a volunteer military can be seen to self select for incompetent leadership due to the nature of peacetime vs war time army confounded by authoritarian type that will self select for military careers.

One can examine the US civil war with such an eye and note that very few Professional officers turned out to be any good and in the case of Sherman and Grant were ironically terrible officers until there was a war to fight yet were terrible "professional" officers.

Conscript vs Volunteers is a bit of a red herring, the issue is are you really willing to militarise your society through conscription, and how bad things are that it becomes a good idea.

Note that the 60/70s Conscript US army did quite well verses the Conscript North Vietnamese and volunteer Viet Cong, compare with the string of failures of the professional/volunteer French army verses the Vietnamese.

Sure they are, if you actually start looking closely at the history of the military and warfare it's full of astounding acts of stupidity and incompetence.

Here's a good book on the subject, required reading for most officers in the British military and frankly pretty good for anyone in a management position.
http://www.amazon.co.uk/Psychology-Military-Incompetence-Pimlico/dp/0712658890