|Reloading is necessary if your gun isn't loaded (called loading) or you've run out of bullets.|
If you're in a gunfight and you empty your gun, you'll need to reload it. This is a skill you should practice whenever possible.
If you have a shotgun you can also practice topping off the magazine while there's a lull in the action.
It pays to have as big as a magazine as possible, but in my state the government limits only law-abiding citizens to 10 rounds and criminals don't have a limit, because they're criminals.
Practice in various scenarios