There are many axes of complexity. Routine line of business systems, say an inventory management system for a car dealer, with a proper architecture costs should be additive instead of multiplicative, a certain cost to develop features such as “autocomplete control that draws values from a database row” and a certain cost to deploy that control. Double the number of screens using the same features and you double the cost but it feels like sub linear scaling because for the second tranche of forms you don’t have to redevelop the components and it can go much faster.

That ideal can be attained and you can be in control in application development but often we are not. When you are in control the conventional ideas anout project management apply.

As you get very big you start having new categories of problems, for instance a growing social system will have problem behaviors and you’d wish it was out of scope to control it but no, it is not out of scope.

Then there are projects which have a research component whether it is market research (iterate on ideas quickly) or research to develop a machine learning system or develop the framework for that big application above or radically improved tools.

A compiler book makes some of those problems look more regular like application programs but he project management model for research problems involves a run-break-fix trial of trying one thing and another thing which you will be doing even if you are planning to do something else.

Livingston, in Have fun at work says go along with the practices in the ocean you swim in (play planning poker if you must) but understand you will RBF are two knobs on run-break-fix: (a) how fast you can cycle and (b) the probability distribution of how many cycles it will take. Be gentle in schooling your manager and someday you might run your own team that speaks the language of RBF.

Unit tests put a ratchet in RBF and will be your compass in the darkest days. They enable the transition to routine operation (RBF in operations is the devil’s antipattern!)

They are not a religion. You do not write them because a book told you so, you write them for the same reason a mountain climber wears a rope and if you don’t feel that your tests are muda, waste as they say in Japan.