It's a good idea to purchase the night vision goggles as soon as they become available. They allow the thief to see in poorly illuminated conditions without the danger of creating a light that could attract attention, like the flashlight.
Because there are several houses with dark furniture, the night vision goggles can be especially handy when searching for every last lootable item. While it is obstructive during daylight, it isn't even necessary by then.
Note: The flashlight and night vision goggles are activated with different keys/buttons; therefore, a player can continue to use both if they choose.