My understanding is that the overwhelming majority of recycled material just ends up with the rest of the trash.
I'm asking because over the years I've hoarded an incredible amount of the plastic flower pots that house plants come in, and I've recently admitted to myself that I'm never going to use them. I'd chuck them all into the recycling, but they're all dirty so I have to wash each one individually, and I'm not sure if there's any actual point in doing that.
There are a couple of uses, depending on where you are. While the vast amount of plastic isn't recycled in Sweden, it is burned in a furnace in order to create district heating or electricity and the ashes get landfilled.. Not a brilliant solution, but far better than just sending it off to a landfill as is. By separating stuff it is helpful for making sure that the unsorted garbage can be mixed appropriately to burn with no kindling, plastic is very flammable. Glass and metal are good to recycle anywhere. Paper and cardboard is also fine to recycle a handful of times. Separating organic matter is also useful for composting, granted it is also used to create methane gas, so I'm not sure if it is good as a coal sink.
Used to be a really good system of reusing glass bottles for drinks, same bottle for all brands just wash them and slap a new sticker and bottlecap on there. But that is dying out in preference to PET bottles. Shit sucks.