Agile non-negotiables are those software engineering practices that you'd be crazy to go without.
Unit Testing: Knowing your code works
Refactoring: Paying down your Technical Debt
Test-Driven Development: Knowing what your Goal is before Coding
Pair Programming: Tightly binding review and development together
Continuous Integration: Making it Production Ready
I'm a little crazy. I don't always use all of the above practices. I try to but my desire to be a hero and get things done quickly overcomes my sensible side. I think most people do this too. There are always outside influences that can seduce a developer into over promising.
The argument for ignoring those outside influences and always practicing the above agile non-negotibles is that you will have:
- better quality code,
- more consistent deliveries, and
- less bugs.
Stop worrying about taking three days to develop something that might have took two days had you left out unit testing or refactoring. That is only a short term savings. Consider how long it will take to fix a missed bug or add a new feature next year.
Using the above practices is an investment in the future of your software.
