Which release schedule would this be
 https://buyersguide.macrumors.com/#Other
April , September , September , September.
Fall and September kind of go together .
If Apple is mainly doing an internals bump, then there may not be much from the supply chain to leak .  Same battery , screen , case , etc wouldn’t make ‘ rumor waves ‘ in supply chain .   If just added better ( lower power consumption) radio and/or  a power optimization process shrink on CPU  then it would present low rumor profile , but substantial enough for a version bump .   Battery life was always a major issue . It has been ‘ good enough ‘ but better would just solidify their lead .
( maybe ceramic case but could hold that back at release time for later roll out )