Well Vern, you are opening another can of worms.
FWIW, "clearing" my house would be a pretty simple operation. The master bedroom/bathroom is a full 1/3 of the house. More than likely, that is where I would be. From the doorway of that bedroom I can see 3/4 of the house (master bedroom, living room, kitchen as well as every door leading to the outside of the house (front/back/garage). If I seriously thought someone was in my house, the would have to be in one of the other two bedrooms and I would not attempt to go after them. However, this is not a usual situation. Far more likely would be when you either hear something, or have some reason to believe everything is not normal. You don't KNOW someone is in the house. You are not "clearing" the house in the sense being discussed here. You are investigating a noise or just giving your house a once over.
However, the thread isn't about clearing buildings: it is about weapons mounted lights.
The point I am trying to make is that a weapons mounted light is not a gadget. It isn't some mall ninja gear. It is a legitimate piece of equipment and serves a purpose for anyone that is intending to use a firearm for personal defense. If you (generic you, not you Vern) try to actually run a gun at night, you quickly learn that it requires a great deal of skill. It isn't something you try once or twice in the house with an unloaded gun and you are good to go. You quickly realize that a lot of this skill can be made up for by having the light mounted on the weapon. This is almost essential if the weapon is a shotgun. It is easy to pick up your shotgun at home, hold a flashlight next to it and say bang. It is another thing to actually try to search a building with a flashlight in one hand and a shotgun in the other as well as actually trying to fire live ammo at a target with a shotgun and a flashlight. If you (generic you) actually try this, it will be immediately obvious.
This is in addition to having a light anytime you pick up the weapon. There is nothing to forget. Nothing to think you don't need until you do need............