None. Not even a one-off.
Major campaigns I've played in (some overlapped, and I wasn't around for the entire duration of some):
1e - highest level PC = 11th, highest party average about 9th (ten years) {my highest = 11th}
1e - highest level PC = 7th, highest party average about 5th-6th (seven years)* {my highest = 6th}
3e - highest level PC = 15th, highest party average around 13th (ten years)* {my highest = 11th}
1e - highest level PC = 10th, highest party average around 8th (seven years, still going) {my highest = almost 9th}
Major campaigns DM'ed:
1e - highest level PC = 10th, highest party average about 9th (ten years)
1e - highest level PC = 12th, highest party average close to 10th (twelve years)
1e - highest level PC = 9th, highest party average about 7th (six years, still going)
* - these were single-party linear campaigns with few if any spin-offs or side parties. The other campaigns all had multiple parties being played alternately, sometimes interweaving, merging, splitting, side parties being played now and then, etc.
Lan-"10th level and counting"-efan