Steve,
In my experience, there's no accounting for the presence of old blocking, until one figures out the history. Old window and door opennings that have been closed is one source. I've also had to deal with what appeared to be old fire blocking, but that is quite rare, in my experience, in my area.
The point is, the buried framing history is a big part of what makes rewires really hard to bid accurately. Collateral damage to wall surfaces is inevitable, and the art is to do it to the side of the wall that costs the least to re-decorate.
Early on, I picked up an Auger Extender Kit that was made by ITT Holub Industries, Product No. 18-653. (I can't find them on the Web) The parts in the kit were used on either end of a section of 1/2" water pipe. . .a drive end and a chuck end. I got a collection of 2 and 3 foot sections of water pipe with couplings and I then had a bit that I could extend to 30 (thirty) feet. I actually put it to use at that length once.
Most commonly, I'll use it to go from the basement to the attic of a two-story wood frame where I'm certain of the alignment of the walls.
The drive end of the adapter finally twisted off (it was only 3/8", as manufactured) so I cut off a piece of a 1/2" hex shaft extension for a hole saw and brazed it into the end of the short starter section of water pipe, and I was off and drilling again.
It occurs to me that a chuck could be brazed into a short starter section of pipe, as well.
Once the bit arrives in the attic, use pipe wrenches to turn off the starter section, push a fish tape down the pipe, and then go to the basement and take out / disassemble the sections of pipe.
This setup, though somewhat time consuming, has made the hard job easy and the impossible possible.
