The Excitement of a trip and making a dive can work some folks into a frenzy of activity. This excited attitude can lead to rapid arm movements and fin kicking which in turn causes rapid breathing and depletion of air supply. This means your dive gets cut short.
A short rapid trip over an area probably means that many of the animals and features that make the dive interesting were hurried right by unnoticed.
On the way down, divers should maintain neutral buoyancy, and once on the bottom, check their gauges and signal each other. This short procedure allows the group to stay together so no-one is trying to catch up.
It also gives everyone a chance to get oriented to the new environment and take a few slow deep breaths before calmly setting out to dive the planned route. With a more relaxed group, the dives will last longer, everyone will see more and divers will be less fatigued at the end of the day.