At 3 months old, all of my girls were still eating every 4 days. My oldest (not my biggest), at 8 months, is the first to start slowing down and I'm starting to think just now about moving to weekly feedings. My others, between 4 and 7 months, are showing zero signs of slowing down and I will continue feeding them every 4 days until they tell me otherwise.
Like Expensive hobby said, appropriately sized meals are the key. There aren't many good reasons, especially while they should be growing like weeds, to keep their bellies overly full or overly empty. Frequent smaller meals are more beneficial than infrequent larger meals.
The only reasons I can think of to back down to biweekly meals right now would be ones that are more beneficial to you than to them, IMO.