Distance judgment is crucial to hitting game with a bow -- even a powerful bow with lightweight arrows. A laser rangefinder eliminates guesswork with the press of a button.
Still, using a rangefinder requires skill and planning. Hunting from a treestand or ground blind, predetermine and memorize distances to landmarks like rocks, trees, and grass clumps. You won't always have time to use your rangefinder directly on deer. And remember, actual distance never accounts for upward and downward shooting angles. Arrows hit high at steep angles, something you must learn to compensate for in advance.
In stalking situations, I don't always use a rangefinder immediately before the shot. Instead, I range the animal from afar, range the place where I plan to shoot from, and then subtract the second distance from the first. This gives me the distance of my shot in advance. When I do get close, I don't have to fumble with my rangefinder before drawing my bow, which saves time in making the shot and reduces the chance that the animal will detect me.