Lanyards have their origins in combat situations. They were used to help keep one's pistol close to him at all times and available in case of emergencies. Another benefit is that lanyards prevent soldiers from losing their pistols as well.

Certain situations that may be beneficial to have a lanyard on the pistol is when one is sleeping in the sleeping bag. This makes the pistol almost immediately accessible without excessive groping in the dark.

There are some shortcomings to lanyards though when a person is in the thick of things. For instance if a person is running around for whatever reason whether being pursued or doing the pursuing, their lanyards may get stuck on things very easily such as branches, and things of that nature.

If used in a heavily wooded or dense area, this may pose a problem too. Lanyards can also potentially be used against someone by another person. They can be grabbed onto and used to essentially steal away one's weapon or perhaps even drag an entire person around.

This may be the reason why, in real life situations, lanyards are not required in live combat situations. But in some cases they are still used to the degree they can provide utility without sacrificing someone's safety and well-being or putting them in harms way.