When I was working I had two yorkies
so they kept each other company. They were always very good together (for 13 years!). Now that I am not working, I spend more time with my little guy (adopted recently, almost 7) so he's fine without a buddy.
It's a personal choice.
It does take more time but was worth it to me. Cost can be a factor, too, since it means two dogs that have to go to vet for regular care.
I've been thinking about getting a second one, too, but not totally sure about it.