Earlier quoted context omitted.
I can only speak to my experience. The friction involved in slicing those pieces of work ends up creating a sizable force. I'd love to hear more about how you've handled it well.
Well that force is the design effort. “How do I break this up in parts?” “I need to test this”, “I need to isolate that or it’s not manageable”. Otherwise you’re just cowboy-coding, shaving yaks along the way to implementing the Epic Goal, leaving a trail of legacy
Again, this is just my own experience, but what I've found is that, once you break the valuable and large piece of work down into small pieces, those small pieces don't get prioritized, because each piece on its own isn't tremendously valuable, so they get outcompeted by other small pieces of work that deliver their own standalone value earlier on. I think the best answer to this is to advocate individually for large work of this type, but I would rather be able to work it into a repeatable process.