Whether a material should be recycled depends on weighing the benefits against the costs. The main benefits are that recycling conserves finite raw materials such as ores and crude oil, usually uses less energy than extracting and processing new material, and reduces the amount of waste sent to landfill. Using less energy from burning fuels also means less carbon dioxide is released.
The costs and problems are just as important. Waste has to be collected, transported and sorted, which needs people, vehicles and energy, and different materials must be separated before they can be reprocessed. Mixed plastics are hard to separate. Recycled material can also be poorer in quality, so it may only be good enough for less demanding products, and there is no point recycling if there is no market for what is made.
Aluminium shows how the balance can work. Extracting aluminium from its ore by electrolysis needs a great deal of electricity, so recycling scrap aluminium is much cheaper. For a cheap material such as some plastics, the cost of collecting and sorting may be close to the cost of making new material, so the decision is harder.
To evaluate a recycling scheme you compare the benefits, such as saving raw materials, energy and landfill space, with the costs of collecting, sorting and transporting the waste. You then make a judgement and support it with evidence.