Originally Posted by
NWIFlyer
...it can be beneficial to have staggered renewal dates when always travelling together because if for any reason status is temporarily lost one partner can guest the other.
This would have been my point exactly, but for a different question/argument: If their plan is to always travel together and accrue the miles simultaneously, then why would both of them need Gold in the first place? (doesn't a gold's "plus one" always get lounge access and gold check-in or does it have something to do with baggage allowances etc.?)