The microwave is a cooking tool designed around precision. Punch in how long you need your food to heat up in a microwave, and that’s what it will do; no more, and no less.

But for all the exactitude that governs the microwave — and that the microwave tries to impose on our food and our cooking — the reality is that things can’t be so neatly stuffed into a convenient digital box. Life isn’t binary, so many microwaves feature an “add 30 seconds” button to give us humans the wiggle room we need within the otherwise unbendable numbers of the countdown clock.

It’s a button that stands in almost caveman-y opposition to the intended functionality. Instead of calculating the perfect amount of time to reheat or cook your food, it turns out that the best way to actually use a microwave in real life is to just force it to turn on and keep going until you think that the food is ready. And if it’s not? Well, you just add 30 seconds more.

Microwaves are almost omnipresent in kitchens nowadays and are comparatively high tech compared to a stovetop range or an oven, which have been largely unchanged in their basic functions for centuries. The basic technology is simple: microwaves bounce radio waves to agitate the water molecules in your food in turn creating heat, thus transforming your leftover pasta or frozen dinner into a quickly accessible feast.

When you’re cooking with an oven or an open flame on your stove, there’s an element of unpredictability baked in. Sometimes that batch of cookies will need an extra minute; sometimes your eggs burn because you overestimated how long they would take to cook. It’s hard to put most recipes or food items into an exact, scientific box.

And yet, that’s what we try to do with the microwave. It’s not a coincidence that most food destined for the microwave is premade: usually something that comes from a box, complete with specific timing and directions, or leftovers pulled from the fridge, the remnants of a prior meal being zapped into a specter of its former self.

But the “add 30 seconds” button is a crack in the cold digital armor of the microwave, an area of control that lets users go beyond their allotted time, to sneak in a few more seconds to achieve the perfect results. It’s a reminder that life isn’t always exact or predictable, and that time is on your side.

Because sometimes, a few extra seconds can make all the difference.