Nothing is forcing you to go buy double everything each time you shop.
If cash is tight but you want to implement this scheme, buy an extra unit of one household item (e.g. laundry detergent) your first trip. Hext time, choose another item (e.g. trash bags).
Eventually you've got a backup unit of every item, and you're now just buying your one item on the same consumption schedule, except now instead of replacing the item you're replacing the backup.
Nothing is forcing you to go buy double everything each time you shop.
If cash is tight but you want to implement this scheme, buy an extra unit of one household item (e.g. laundry detergent) your first trip. Hext time, choose another item (e.g. trash bags).
Eventually you've got a backup unit of every item, and you're now just buying your one item on the same consumption schedule, except now instead of replacing the item you're replacing the backup.