  The JCMT Gould Belt Survey was one of the first Legacy Surveys with the James
Clerk Maxwell Telescope in Hawaii, mapping 47 square degrees of nearby (< 500
pc) molecular clouds in both dust continuum emission at 850 $\mu$m and 450
$\mu$m, as well as a more-limited area in lines of various CO isotopologues.
While molecular clouds and the material that forms stars have structures on
many size scales, their larger-scale structures are difficult to observe
reliably in the submillimetre regime using ground-based facilities. In this
paper, we quantify the extent to which three subsequent data-reduction methods
employed by the JCMT GBS accurately recover emission structures of various size
scales, in particular, dense cores which are the focus of many GBS science
goals. With our current best data-reduction procedure, we expect to recover
100% of structures with Gaussian sigma sizes of $\le$30" and intensity peaks of
at least five times the local noise for isolated peaks of emission. The
measured sizes and peak fluxes of these compact structures are reliable (within
15% of the input values), but source recovery and reliability both decrease
significantly for larger emission structures and for fainter peaks. Additional
factors such as source crowding have not been tested in our analysis. The most
recent JCMT GBS data release includes pointing corrections, and we demonstrate
that these tend to decrease the sizes and increase the peak intensities of
compact sources in our dataset, mostly at a low level (several percent), but
occasionally with notable improvement.
