We have 7 keys for our house (the same key does the front and back doors)
1 on dh van keys
1 on my car keys
1 in ds's school bag
1 in inside lock on front door
1 as a spare on the kitchen hooks I use when car sharing
1 with dog walker
1 on Keyring with shed keys also on the kitchen key hooks
Back door doesn't need a key as it is a thumb turn to lock it.
Quite happy for any burglar to find a key, steal what they want and get out without waking us!