I think at around 2.5 they start needing a bit more. I'm not saying that if you don't go they will suffer, just that I think my DD needs more than I can give her at home. She's been going to day care 3 days a week since 9 months old. She's now 2.5 and comes out with stuff I've never taught her, and would never think to teach her. We've had bad drop offs that have broken my heart, but now she runs off to play with her friends.
I live in the country too and care is a 20 minute drive away so it's time consuming sending her. But she does love it.