I have been running placement schemes at the House of Commons now for two decades. One entails spending the third year of a four year degree (in British Politics and Legislative Studies, BPLS) on placement with an MP. Another, a more recent scheme, entails students on three year single honours degrees spending one semester - the penultimate semester of the final year - at Westminster. With the former, the placement year is an integral part of the degree programme; with the latter, candidates are selected by interview in the second year. Both my experience and a C-SAP-funded survey in 2004-5 of our students and placement providers reinforce the findings of previous studies as to the benefits of experience-based learning. Experience also demonstrates the challenges posed to any organisation providing opportunities for placements.
Norton, P. (2008). Parliamentary placements: the benefits and challenges. Enhancing Learning in the Social Sciences, 1(1), 1-9. doi:10.11120/elss.2008.01010004