Several times during the year there are festivals and holidays that require incense burning. Although I feel like its on going all year long, you can see an increase around these times. Burning paper money (not real) as an offering is also common.
Someone on our floor in our apartment building burns incense all the time. When I was pregnant I could hardly stand it and could even smell it inside my own home. Now that crazy pregnancy nose is long gone, I only smell it occasionally in the hall.
There are built in alters like the one in these pictures and also many people have small alters in there home. I didn't take this last photo, but have seem many like this in homes and outside.