[brundolf]

I would frame this as:

1. Make sure there's always a trap-door where you can implement special cases

2. A good way to always have (or to create) a trap door is to compose out of smaller pieces; then if you need something to be different in one case you just "reassemble it" with pieces added, removed, or rearranged

In the author's case, maybe CRUDController's key pillars of functionality could be broken out, still bundled together as CRUDController for normal cases, but then for special cases they could just assemble custom solutions out of those pieces instead of bending CRUDController into shape