**Golden Rule (what it is):**
 *A single guiding decision: **adapt when you can; grow when you must.***
 In GrowNet: if a new input truly doesn’t fit existing “drawers” (slots), **make room** (add capacity). Otherwise, just refine what you’ve got.

**Where this shows up elsewhere (one-liners):**

- **Your life:** routines work until they don’t → learn a new skill or change the routine.
- **Teams/companies:** current staff/process handles demand until it doesn’t → hire or create a new function.
- **Software systems:** one service scales until it can’t → split into a new microservice or add a shard.
- **Cities/infrastructure:** roads handle traffic until they don’t → add a lane, subway line, or new route.
- **Biology/brain:** existing synapses encode patterns until a new one persists → grow/rewire connections.
- **Education:** a course covers needs until new topics emerge → add a module or a new class.

**In one sentence:**
 **Use what exists when it still fits; add something new when it no longer does.**