Asturias 56
I think you were right to a degree, as many did correspondence courses, and if not officers, even worked outside the wire to break up boredom, especially those captured early in the conflict. My dad arrived via Bomber Command in late 1943 and escaped in 1945 from a marching column, though his motives were that due to low level strafing by US /RAF aircraft as it was becoming very dangerous to stay, rather than disrupting the German war effort. They were on the run for 15 days, and he watched the bombing of Hamelin during this time on his 21st birthday, eating raw potatoes, as he reminded me on my own 21st.
Kind regards
Mr Mac