The recent discussions got me to thinking about how the current bands
are partitioned. Taking a quick look at the current US allocations
indicates these portions of the HF bands in which phone is not allowed
(what I would have called "CW bands" in another era):

160: None
80: 3500-3600 20%
40: 7000-7125 41%
30: None
20: 14100-14150 42%
17: 18068-18110 42%
15: 21000-21200 44%
12: 24890-24940 40%
10: 28000-28300 18%

The conclusion is that, with some exceptions, an individual who is only
interested in running SSB is excluded from around 40% of most of the US
allocations. Is that reasonable? Is this bandplan maximizing the use
of the resource?

One definition of "optimum allocation" is providing the same usability
for operators of every mode. In order to accomplish this, one needs to
know the number of people who wish to use each mode. It's not possible
to directly and accurately obtain this number, but perhaps counting the
number of QSOs in progress might approximate it.

In the absence of any data, I'm not going to speculate about whether 40%
is a reasonable number. Have there been any attempts at measuring
utilization in an objective way?

73, Steve KB9X