Never will be done
I'll be done when my safe is full. Of course, I'll start again once I buy the new safe.
I have a lot of firearms, and have recently decided that I should probably sell or trade anything I haven't fired in the last five years. a corollary of this rule is to reduce the number of calibers in my collection; I'm a reloader, and don't reload for all of the calibers I currently shoot or own.
I'm a shooter, not a collector, and the above rules will provide the cash and space for new firearms that suit my current tastes - and will be more likely to be fired frequently.
My current plan is not to reduce the number of firearms I own, but to modify my collection to include only regularly-fired items.
Phase Two will probably be reduction of my arsenal to(perhaps) a half dozen firearms that cover the spectrum of my shooting interests; but I don't intend to implement Phase Two until I grow up.
My wife said "one more and I'll be done