By nature, carbon becomes useless (clogged) after a relatively short period of time. I stopped using carbon in my system and noticed absolutely no difference. The only time carbon might be used is to remove medication, after the medicating period. An added benefit to not using carbon is that you free up space for additional mech/bio media.
Ammo chips are a bandaid that should never be used as a normal part of filtration. Removing ammo is counter productive since the bio load (nitrifying bacteria) require ammo to sustain the nitrogen cycle. Replace the ammo chips with bio media and you'll naturally "remove" ammo, along with nitrites.
Any system that has ammo greater than zero (aside from the week or two after adding new large fish, which is a different topic) simply does not have a sufficient bio load. In this case better bio media, or more bio media is the only correct fix.