Earlier quoted context omitted.
Places that can't have code leave the work site still do not use AI.
Most places I know that have strict on-premise/air-gap requirements are just investing in on-premise AI and open source harnesses instead. The only ones that don't are the typical places that are slow to adopt technology in general (usually because they can afford to due to historic moat).
LLMs can be nice sometimes, but not necessary. Internal teams with "not invented here" syndrome currently working on that stuff are ultimately wasting money until the dust settles a bit more.
Those long deadlines have nothing to do with implementation. It's the game of telephone and accountability bottlenecks. You still want to retain your most experienced devs and give them plenty of time to work. Writing the code was never the bottleneck. A good dev team has balanced experience of the business and the code, not just the code, and certainly not the kind of code an LLM generates. Most of the decisions by those devs happens outside the codebase.