Why is the question asked by the OP phrased as if work exp has a minimum value that needs to be met? Surely you do enough work experience to satisfy yourself that medicine is a vocation that you can truthfully see yourself doing for decades to come, not just to be able to waffle convincingly through a 20min interview? I did a total of four weeks full time shadowing, with both GP's and hospital docs, and have eight months of volunteering at a hospice and a hospital, plus working part time at a GP surgery this year, but if I had the opportunity to spend more time shadowing docs I'd jump at the chance. If work exp is something you endure 'to get into medicine' rather than the chance to learn more about medicine and spend time with fantastic doctors and, more importantly, interesting patients... why are you applying for medicine?