Divide ground beef into 4 (½-pound) or 6 (1/3-pound) portions. When handling the meat, gently form into patties of equal size (1-inch thickness) without overworking the meat. Gently create a divot with thumb in the center of each burger. Arrange on a plate in a single layer, cover and chill for at least 1 hour and up to 6 hours.
Heat the grill to high (gas or charcoal); 375-400 degrees F. Brush and oil the grill. Lightly brush one side of the burgers with olive oil, place them on the grill (olive oil side down); brush the top side with olive oil. Cover, cook for 2-3 minutes to sear the bottom (you should see grill marks).
Flip and cook an additional 2-3 minutes for rare, 4-5 for medium-rare or 6-7 for medium doneness as measured with an Instant Read thermometer. If adding sliced cheese, add 2 minutes before burger is finished grilling. NOTE: time will be less if cooking 1/3-pound burgers.
Remove and allow to rest 5 minutes.
Assemble the burger with a slice of lettuce between the bottom bun and the burger (helps keep the bun intact) and condiments or toppings on top. Salt and pepper if desired.
The USDA guidelines state ground meat should be cooked to an internal temperature of 160 degrees. Meat does continue to cook while it rests off the grill so usually they can be taken off the grill slightly under 160 degrees.