@MustardMitt
DH and I are pillow punchers so I replace them quite regularly. I could probably do it less often if I spent more in the first place!
Maybe every 3-6 months, if they’re not too gross they get relegated to Visitor Pillow status; if they ming I take them to the tip.
Seriously? Or is that a typo and you wrote months when you meant to say years?
Ours are the shaped foam ones from IKEA and I think they're about 10-12 years old and seem fine.
Old pillows if we have any get repurposed as cat beds and end up in the bin when there's the inevitable accident or dirty protest (we foster for a rescue so have quite a few comings and goings of often troubled cats and kittens).
Most recycling centres don't accept bedding and all our non recyclable waste is incinerated in a waste to energy plant, do no landfill issue.
So rescue organisations might accept old pillows, not that pillows need changing multiple times a year anyway.