  The effective field theory of cosmic acceleration systematizes possible
contributions to the action, accounting for both dark energy and modifications
of gravity. Rather than making model dependent assumptions, it includes all
terms, subject to the required symmetries, with four (seven) functions of time
for the coefficients. These correspond respectively to the Horndeski and
general beyond Horndeski class of theories. We address the question of whether
this general systematization is actually effective, i.e. useful in revealing
the nature of cosmic acceleration when compared with cosmological data. The
answer is no and yes: {\it there is no simple time dependence of the free
functions} -- assumed forms in the literature are poor fits, but one can derive
some general characteristics in early and late time limits. For example, we
prove that the gravitational slip must restore to general relativity in the de
Sitter limit of Horndeski theories, and why it doesn't more generally. We also
clarify the relation between the tensor and scalar sectors, and its important
relation to observations; in a real sense the expansion history $H(z)$ or dark
energy equation of state $w(z)$ is $1/5$ or less of the functional information!
In addition we discuss the de Sitter, Horndeski, and decoupling limits of the
theory utilizing Goldstone techniques.
