In a busy working household, a lot depends on the water heater. Showers before work, dishes after dinner, laundry on the weekend, all of it runs through that tank. A household without hot water is on the spot, which is why the early call is worth so much here.
Water heaters usually show signs before they fail, like cooler water, shorter showers, a pilot that needs relighting, or rust or moisture at the base. Whoever lives with the tank tends to notice first, and acting on it early gives you time to choose a repair or a replacement calmly.
The tank gets a close look at its age, its condition and its size against the household using it. If a repair makes sense, that's the recommendation. If it's time for a new one, you'll hear it plainly with the options laid out. Everyone gets the same clear answer.