Fragrance strength is influenced by much more than how much fragrance oil is used. Different aroma materials evaporate at different rates, some scent families naturally project farther, and the wax formula and warmer temperature can change how a fragrance performs.
Your own nose matters too. A sharp citrus, mint, laundry, or spice blend may seem much stronger to you than a soft vanilla, musk, or woody scent even when both were made carefully. That is why 'strong' is not always the same thing as 'high quality.' A well-made fragrance should smell balanced and recognizable, whether it is intentionally bold or designed to stay closer to the room.