The high proportion of  common sites that are highly persistent over time (Pc | s > 5, =~ 35%relative to all high needs sites (Ps> 5 )is a reasonable explanation of why they appear clustered spatially.  I  suggest, however, that this effect would need to be better understood in context to other social, economic or physical  determinants. Yet, the emergence of the observed clustering effect is likely to assist virtual street audit projects in urban planning decisions.