Not necessarily. This makes a lot assumptions like you are going to have time to change the state of your shotgun when you need it. If you are racking a shotgun at the start of your encounter then you were starting with an unloaded gun (or ejecting unspent ammunition.) If you want to use to sound to reliably intimidate people you ether need to issue verbals commands (“I am armed and I will shoot you…”) or begin shooting them.
2. Shotguns don’t need to be aimed.
Depending upon the distance and the load the shot will strike in a small cluster a few inches across. Shortening the barrel or increasing the distance will cause the pattern to spread out more, but will also reduce the penetration of each pellet. Realistically you need to get as many pellets into the vitals as possible so wider spreads of shot are less likely to produce stops in human targets.
3. Shotguns will knock a bad guy into the air.
Nope. Physics tells us that if the shotgun had enough power to lift the target it would also have enough recoil to lift the shooter. Shooting people who are off balance might get knocked over, but nobody is going to go flying though windows.
4. Shotguns are more deadly than rifles.
A trigger press of .00 buckshot is like shooting a lot of little handguns. Assuming all the pellets are on target you generally produce a number of low velocity wound tracts. This means that any tissue that is actually touched by a pellet dies, but the surrounding tissue is undamaged. Rifles fire one bullet at higher velocity creating a larger permanent cavity. The subjective “deadliness” has more to do with the circumstances of the shot (distance and shot placement) rather than a hard fast rule. Both shotguns and rifles are more than capable of killing people.
5. Shotguns require less training to operate effectively.
Because of the higher weight, recoil, limited ammo capacity, and manual controls shotguns require more training to operate. People that are new to shotguns frequently “short stroke” inducing stoppages. Less critically things like reloading and ammunition selection (select slug drills) do require a fair bit of practice to master.
I would not argue that shotguns are not effective self-defense weapons, but they do not live up to the hype and in most circumstances are not as good as having a semi-automatic rifle. Despite the informal training supplied by Hollywood and video games, they do no live up to their billing.