I’ve had a long career in this silly business. All the way along, one of the sillier things that people have said is this: “Testing slows down the project.”
This is roughly equivalent to saying that looking out the windshield and attending to the dashboard slows down the journey.
Sometimes people say that discovering problems slows down the project, but that’s not true either. Discovering problems can dispel the illusion that everything’s fine at the current pace, whereupon responsible people might decide that the project needs to slow down.
Having good tests are like having great brakes on a race car. You can go faster knowing you’ll be able to slow or stop without crashing.
I can see how tests or checks might be usefully compared to instruments on the dashboard, or to things to look at through the windshield. Upon seeing some alert, or some sign of danger, we might choose to apply the brakes.
I don’t see how having tests (or checks) are like brakes. Neither tests nor testing control the project; they don’t slow it down.