We have a 2015 Ford Expedition, not with Sync 3 though. But the maps were very up to date when we bought it new in Jan 2015, and we live in a rapidly growing area. Certainly much, much newer than 10 yrs. I really like it now that I have learned how to talk to her. She is particular about answering her questions in the way she wants it when seeking directions.
I also have a 2012 F350. The maps on it are still pretty accurate, just missing new streets built since I bought it. Have been considering updating, but just not missing enough yet to make me do it. I think an update every 4-5 years is good enough.