Cecil Moore wrote:

SNIPPED

Well, of course, you just said it again. :-) The standardized
S-unit is 6 dB. Therefore, "4 S units" over a dipole is 24 dBd
gain for your omnidirectional vertical monopole. (That's ~17 dB
more gain than a three element Yagi has over a dipole.)

Cecil ... you are out of context [again].

The earlier post referred to long haul DX on the lower bands where a
three element Yagi at optimum height is not easily within the realm of
possibility for us mere mortals. [ Let's see, 1/2 wavelength high on 80
meters is 135 feet, boom length for a three element Yagi at 80 meters
will approach 100 feet, You will need a football field of free space and
quite a few bucks, and the approval of several engineering firms, the
approval of you town building inspector, and the wrath of your neighbors
to compete with a simple vertical over a decent ground.] C'mon Cecil!!
Cecil ... apples and oranges ... do not enhance your reputation.

Many of us use verticals on 160, 80 and 40 meters simply because they
blow the pants off of horizontals on those frequencis for long haul DX.