Seriously Jim - I have 2 anchors - one 5kg bruce - for normal use!
I don't have the miles of chain, but enough to be more than 5KG (prob 7kg)and keep the anchor at the buoy on retrieval! (so weight rather than length!)
I also keep a folding 5KG bruce onboard for emergencies. I guess the scenario is, you cut your rode as anchor stuck - so head in, engine issue and you need your anchor to stop you drifting in to rocks \ traffic - where is you anchor?
Also, a second anchor can be deployed to stop sway when at anchor in shallows, i.e. the harbour.
Rob