If I had had my way, both time I tested for ShoDan would have been in the 0-5 minutes bracket!!!!!
The first time was about 20 minutes, 20 techniques, 4 Jiyu Waza and then 13 Jo Kata. My Nidan was longer though, Kamae, Kihon Dosa, Rensoku techniques (Kokyu Nage), 5 Jiyu Waza, 20 techniques, 13 Jo Kata and 31 Jo Kata.
The second time I took ShoDan (different organisation) I also took my Instructor exam at the same time. There were 3 of us testing - one to NiDan, another doing his instructor exam, and me doing both ShoDan and Instructor. We were on the mat for a total time of 2 1/2 hours on a blistering hot July day. Most of it was done together, with us being Uke for each other too.
I voted 30-60 minutes, but it depends on the organisation and the Sensei.