"The correct interworking of all circuits together is the ultimate goal of a properly tuned DCOE. However, one must be careful as the circuits overlap one another; it is possible to sometimes fix an over-fuel situation in one circuit by under-fuelling in another. "
Weber calls "transition circuit" "progression"
"The Idle Jet is inappropriately named as it primarily controls the cruise mixture more so than the idle mixture. In fact, the Idle Enrichment Screw directly controls the idle mixture. The Idle Jet simply feeds it.
When cruising along a street or highway in a Datsun, the Progression Circuit is the main contributor to the mixture entering the engine. Only the fuel level and Idle Jet are at play. It is very important to select the correct Idle Jet and set the correct fuel level in a DCOE carb so that a suitable air/fuel ratio at cruise is obtained. In the tuning section below, selecting the correct Idle Jet at cruise will be the first and most crucial step. The mixture at cruise can not be tuned by the main circuit nor can it be significantly tuned by the Idle Enrichment Screw. The cruise mixture must be set by selecting the correct Idle Jet AND by setting the correct fuel level. "
So, it does. Now you need data, so you know how rich it is, try another set of jets, and check again.
You are not in the "main circuit" at cruise, rather the "progression" or "transition" circuit.
All the settings are done from know good and correct fuel level settings.