We also do a "100 numbers per block" kind of deal on largish roads with a fair amount of frequency. So even if there's one building on the block, it is all of the 8900 range, and the next block has 9000. (I just walked from 7800 something to 9113 this afternoon, when the bus unexpectedly went to turn off on a road that the map didn't indicate it should, and boy am I glad that's only thirteen blocks.)

Not that that explained the small road scenario, so I'm glad someone else already grabbed that one. :)