How can a startup move fast without destroying code quality?

Answer:

The fix is not choosing speed over quality everywhere; it's deciding upfront which code must be solid and which can stay rough. Authentication, payment processing, and any logic that touches money or user data need tests and a second pair of eyes on every merge; a landing page variant or a one-off internal script usually doesn't.

Why do small, frequent releases make the trade-off safer?

Shipping in small batches turns "did that shortcut break something" into a question you can answer in minutes instead of weeks. A change that touches one feature and ships the same day is easy to trace back if something breaks; a two-week batch of unrelated changes released together makes the failing commit much harder to find. Frequent releases also shrink the blast radius: a bug in an experimental feature reaches a small slice of users before anyone notices, while the same bug sitting in a monthly release compounds with everything else that shipped alongside it.