I enjoy a Dunhill size 4-5 sized pipe as I normally get 1.5-2.0 hours of smoking pleasure from those sizes. I do have a group 6 that takes me about 2-3 hours to smoke. All of my pipes are in the group 4-5 range except the lone 6. I smoke Va, Vaper and Vabur flakes exclusively so those sizes fit my flakes to a tee. When I smoked English blends I preferred group 6 and ODA sized pipes as I felt the larger size gave the blends time to open up as they had more components to them. I used to have a couple of group 3 sized pipes but felt that by the time I was done I still wanted more smoking time.