If you don't like constant reloading and being scared because your near death about all the time then don't. It's unfair and cruel.
But the shotgun works great with almost all enemies, so no wonder.
Kill them like this I think, including you get full hits:
Imp = 1 shot
Zombie = 1 shot
Marine (pistol, rifle, shotgun) = 1 shot
Cacodemon = 2 shots
Maggots = 1 shot
Forgotten ones = 1 shot
Baby demons = 1 shot
Small spiders = 1 shot
Rocket Skeletons = 1 shot
Nightmares = 3 shots
Hellknights = 6 shots
Pinkys = 3 shots? (not fully certain)
Mancubus = 6 shots? (not fully certain)
But the shotgun works great with almost all enemies, so no wonder.
Kill them like this I think, including you get full hits:
Imp = 1 shot
Zombie = 1 shot
Marine (pistol, rifle, shotgun) = 1 shot
Cacodemon = 2 shots
Maggots = 1 shot
Forgotten ones = 1 shot
Baby demons = 1 shot
Small spiders = 1 shot
Rocket Skeletons = 1 shot
Nightmares = 3 shots
Hellknights = 6 shots
Pinkys = 3 shots? (not fully certain)
Mancubus = 6 shots? (not fully certain)