Efficient (Dense) Use of Address Blocks

Karl wrote:

> My request was for 256 Class "C"s. We have consumed almost
> exactly that in a year.

And Alan added:

I did the same. [...] Interpath has
not *QUITE* used up the block, but pretty darn close

Can either of you provide estimates of how densely these blocks
are populated? What percentage of the individual host addresses
are currently used by functioning hosts (or router interfaces)?

Perhaps you're both saying you re-assigned use of these address
blocks quickly, rather than saying you populated them densely
with actual hosts?

One could imagine ISPs (not Karl or Alan, surely!) who might
re-assign blocks of class C (octet-wide) networks when a single
one would suffice. Or they might assign octet-wide networks when
quartet-wide (nibble) networks would suffice; or even quartet-wide
networks when triplet-wide networks would suffice.

I believe ISPs who receive large blocks have a responsibility to
make sure they (and their customers) use them efficiently. How
efficiently, you ask? If you're not getting more than one U.S.
dollar of value per host address per year, you're not using it
efficiently in my book!