Many people like the convenience of leaving appliances plugged in. We don’t unplug everything at our house either.
Anything with a power supply (computers and cell phone chargers are two examples) does draw a small amount of current even when the equipment is turned off, and these small draws can add up with more appliances and over time.
If a receptacle is backwired using its spring clamps, then plugging and unplugging appliances can loosen the contacts over time. When we install or replace receptacles, we don’t use spring clamps – we use the device’s screw terminals, and for this exact reason.
If the receptacle is wired properly, using the screw terminals with contact pads and/or looped wire ends, contact loosening will not happen provided the terminals are properly torqued and that the material in contact with the screw terminals is copper. Copper, like all metals, warms up when current is passed through it and expands slightly under normal use, but when the current is removed, the copper cools and the metal contracts to return to its original shape.
If the receptacle itself is loose in the wall, most likely the box is set back too far and/or the drywall hole is cut too large, and shims may be needed to hold the device firmly against its box. If the box is loose because it was improperly installed, it should be remounted or replaced.
If a receptacle has been painted over, paint can weaken the plastic face of the device. A properly wired, installed, and properly protected receptacle will not fall apart absent a manufacturing defect (fortunately these are rare).
Over time, the recessed spring steel blade contacts that hold a plug can lose their grip and the plug will feel loose. This wear is normal, and means it’s time to replace the receptacle. We usually see receptacle blade contacts start to feel looser after some 15 to 25 years. This is an average based on observation, and several factors are at play in how long a receptacle will properly hold a plug.
An alternative to plugging and unplugging cords is to use an outlet strip, which can be turned off when connected appliances are not in use, and which also provides some measure of surge protection. Please bear in mind though that an outlet strip does not increase the capacity of a circuit, it simply means more things can be plugged into it. But you can turn the strip’s switch on and off without disturbing the receptacle the strip is plugged into.
We are always happy to answer questions. Safety comes first in our business.