The illustration shows what can happen with a DPC cloak that relies upon a textbook relationship between masonry skins.
The course into which the DPC cloak needs to build-in can be too high or too low compared with the adjacent skin.
Approved cavity trays by Cavity Trays of Yeovil are self-supporting and have hinged cavity upstands.
No course alignment worries, and the full cavity width always accommodated.