Just like you would find on a car, furniture has a suspension system and just as you would find in your car, the comfort of the ride has a lot to do with your suspension system. Just like in cars, inexpensive suspension systems exist in furniture as well. Like many things in your purchases, what you don’t see can make all the differences.
Cheap furniture is made with bad suspension. Perhaps the cheapest type is known as Jute webbing. These are essentially fabric straps stretched across a fame, frequently stapled into the frame. Jute webbing can come in a variety of sizes but it will sage quickly and is widely used in “disposable” furniture. The distance between these straps varies based on manufacturers but the cheaper the piece, the wider the spacing.
If you bought a low-cost piece of upholstery and within a year the cushions were sagging, you can bet it was made with jute webbing.