I didn't actually do any theory of learning on my full time uni based PGCE many many moons ago. But what I did get was four contrasting placements (including a primary school and a school for the Deaf) which helped me to decide what kind of school I could see myself in , lots of time to discuss approaches to teaching texts and schemes of work (thus giving me the confidence to plan my onw), an opportunity to think about and practise teaching drama (often landed on English trainees) and a second subject. and learn about form tutoring We had lots and lots of mentoring and feedback and support , both in school placements and at the university - and we built camaraderie. Plus , I still got to be a student and have fun, and wind down and stuff. I was only 20. Teacher training seems so serious, intense and driven now, comparatively. As is teaching.
I still ended up teaching MFL in my first school - but I had German lit in my degree and a fair amount of misguided confidence! On the Facebook group for my main subject people are always requesting full SOWs, lessons , ppts, marked work, moderation. It's like teachers have lost the skills of planning and lost any sense of autonomy. Some of these appear to be unqualified teachers or non specialists shoehorned in. I think a lot of this is the quality of in school training where students follow a departmental scheme and never have a chance to think for themselves.
I think we have to remember whilst quibbling over whether people have A levels in a subject, or even degrees that there are quite a lot of GCSE and A level subjects where the A level might not have existed when teachers themselves were at school and where there are no or very few teacher training routes (psychology, economics, sociology, media, film, medical science, child development all spring to mind). But I do know that getting someone in from the 'film industry' to try and teach GCSE or A level often ends in unmitigated chaos.