  Temperature ($T$) dependent conductance $G = G(T)$ data measured in molecular
junctions are routinely taken as evidence for a two-step hopping mechanism. The
present paper emphasizes that this is not necessarily the case. A curve of $\ln
G$ versus $1/T$ decreasing almost linearly (Arrhenius-like regime) and
eventually switching to a nearly horizontal plateau (Sommerfeld regime), or
possessing a slope gradually decreasing with increasing $1/T$ is fully
compatible with a single-step tunneling mechanism. The results for the
dependence of $G$ on $T$ presented include both analytical exact and accurate
approximate formulas and numerical simulations. These theoretical results are
general, also in the sense that they are not limited, e.g., to the (single
molecule electromigrated (SET) or large area EGaIn) fabrication platforms,
which are chosen for exemplification merely in view of the available
experimental data needed for analysis. To be specific, we examine in detail
transport measurements for molecular junctions based on ferrocene (Fc). As a
particularly important finding, we show how the present analytic formulas for
$G=G(T)$ can be utilized to compute the ratio $f = A_{\text{eff}} / A_n$
between the effective and nominal areas of large area Fc-based junctions with
an EGaIn top electrode. Our estimate of $f\approx 0.6 \times 10^{-4}$ is
comparable with previously reported values \ib{based on completely different
methods} for related large area molecular junctions.
