> but extending an existing service is a bit more like assembly line stuff
(IMO) only if most of the assembly line has to be at least partially retooled every time you do it. No software feature in any but the most basic of systems stands alone.
Which, tbf, a lot of Lean/Kanban software teachings do account for, but most management likes to gloss over.
Service ot service this is less appropriate, but extending an existing service is a bit more like assembly line stuff