We all know the importance of a buoyancy check. Even if you manage to descend, poor buoyancy affects your body's profile in the water, decreasing the overall quality of your dive. Effective air consumption, good ascent / descent control, and an effortless dive all depend on a streamlined position--which can only be achieved with proper weighting.
Despite these facts, rarely do we check our buoyancy. Divers are not entirely to blame, most dive outfits never give us the opportunity in the water, instead rushing the group to depth as quickly as possible.
Next time you are in strange waters, or have unfamiliar equipment and need to perform a weight check, try to be first in the water, either by sitting near the back of the boat or assembling your gear quickly. Then, while waiting for others to splash, quickly check that you are properly weighted. It only takes a moment, and you will still have a chance to adjust weights if necessary.