I tend to think things like "do I really need to own a large pot? Couldn't I just do several smaller batches of food in a small pot?" and "why do I need a chair in my bedroom if I can sit on my bed?"
But I actually try to banish these thoughts--they're almost as dangerous a mindset to get into as that of a hoarder, I think--because the experience of sitting crosslegged on your bed typing on a laptop, with your back aching, reminds you that some possessions actually are a marked improvement to your life. There are a certain number of objects I am alright with being owned by.