for Affinity Publisher
Request:
For prepress workflows it would be very helpful to switch to a preflight mode where you can quickly check what objects are on which colour plates (eg. spot colours)
Problem:
Sometimes there are shadow-effects or overlaying colours and multiplying images that change the otherwise clean constructed set of elements in your layout. For example, you know every text has this global colour and every icon has that corporate-design colours, but where things overlap and blend, you need to know "how dark this black really is" to be successfully printed.
Solution: Of course Indesign has had this feature long ago, and I'm even only using version CS5 from 2010...
But you can also look for Photo's Channel panel: Like Photoshop, you can disable the green and red channels and look how the blue channel looks in isolated mode. in RGB mode this is maybe not as useful but in the prepress-world looking at your isolated CMYK plates is essential!