The decision to search a building involves a risk-benefit analysis. You only do so if alone or as a pair, and only if the likely risk is low. But always search as if someone waits in ambush for you. Pie all corners, horizontal and vertical, correctly. Use dynamic tactics, and when you can't, learn them. With a pistol-mounted light, search with the beam periphery so as not to "search with the muzzle." With a hand-held light, wring out your technique. On an early search, I discovered my preferred light technique resulted in an accidentally depressed magazine release, and an unexpected magazine on the floor.