Your project is past 15 functions. The next one needs different host.json concurrency than the rest, and a connection string nobody else in the app should see. Do you split into a second Function App, or change the values and live with the cross-talk? The answer turns on four constraints, none of which is cold start, even though cold start is the reason most teams give first. When one Function App is too many Microsoft puts the soft cap at 100 event-based triggers per app . Past that, the scale controller silently stops looking: "When your app has more than 100 event-based triggers, scale decisions are made based on only the first 100 triggers that execute." Long before you hit 100, four constraints start to bite: Scale. Every trigger in the app shares one scaling decision (with one Flex Consumption exception below). Deploy cadence. One PR redeploys every function in the project. Blast radius. Every function reads every connection string in app settings. host.json scope.…