  We study the generation of local non-Gaussianity in models of canonical
single field inflation when their backgrounds are either attractor or
non-attractor. We show that the invariance of inflation under space-time
diffeomorphisms can be exploited to make powerful statements about the squeezed
limit of the primordial bispectrum of curvature perturbations, valid to all
orders in slow roll parameters. In particular, by neglecting departures from
the adiabatic evolution of long-wavelength modes (for instance, produced in
sharp transitions between slow-roll and ultra slow-roll phases), we derive a
general expression for the bispectrum's squeezed limit in co-moving
coordinates. This result consists in the standard Maldacena's consistency
relation (proportional to the spectral index of the power spectrum) plus
additional terms containing time derivatives of the power spectrum. In
addition, we show that it is always possible to write the perturbed metric in
conformal Fermi coordinates, independently of whether the inflationary
background is attractor or non-attractor, allowing the computation of the
physical primordial bispectrum's squeezed limit as observed by local inertial
observers. We find that in the absence of sudden transitions between attractor
and non-attractor regimes, observable local non-Gaussianity is generically
suppressed. Our results imply that large local non-Gaussianity is not a generic
consequence of non-attractor backgrounds.
