  We investigate the approach of pure SU(2) lattice gauge theory with the
Wilson action to its continuum limit using the deconfining phase transition,
the gradient flow and the cooling flow to set the scale. For the gradient and
cooling scales we explore three different energy observables and two distinct
reference values for the flow time. When the aim is to follow scaling towards
the continuum limit, one gains at least a factor of 100 in computational
efficiency by relying on the gradient instead of the deconfinement scale. Using
cooling instead of the gradient flow one gains another factor of at least 34 in
computational efficiency on the gradient flow part without any significant loss
in the accuracy of scale setting. Concerning our observables, the message is to
keep it simple. The Wilson action itself performs as well as or even better
than the other two observables explored. Two distinct fitting forms for scaling
are compared of which one connects to asymptotic scaling. Differences of the
obtained estimates show that systematic errors of length ratios, though only
about 1%, can be considerably larger than statistical errors of the same
observables.
