Landing gear door operation

In another online forum, it has been claimed that on the F-18, F-14,
F-4, and possibly F-8, A-7, A-6, and A-4, all the landing gear doors
stay open when the gear are extended. While typically (or at least in
most other military jets), some of the landing gear doors open only
during extension/retraction, and are closed while the gear are
extended.

Can anyone comment on the extent to which this is true? If so, there's
an obvious pattern of this characteristic appearing in fighter/attack
jets which were originally designed for the Navy. Is this due to Navy
"culture" or somehow related to a safety/reliability issue for
carrier-based operation? Or generally, is there some reason that some
jets are designed with gear doors that stay open, while others have
doors that close after the gear are extended? (The only reasons I've
seen that make sense are simplicity versus air drag and, in some
cases, ground clearance.)

Many thanks in advance.

--Elliot Wilen