You’re right to ask — the protocol matters and current evidence is on the side of the AAHA recommendation.

Current consensus (AAHA 2022 + WSAVA 2024 vaccination guidelines):

• Core puppy vaccines (DA2PP) should be administered every 3-4 weeks starting at 6-8 weeks of age, with the final booster at 16 weeks or older.
• The 16-week minimum is the most important. Earlier than that, maternal antibody interference can blunt the immune response. A dog who gets all boosters before 16 weeks may not develop adequate immunity to parvo.
• Rabies once at 12-16 weeks (state law usually dictates), with revaccination at 1 year then per state schedule.

Why some practices still use 2-week intervals: historically, immune theory suggested closer intervals “built up” faster, but modern challenge studies show no clinical benefit and a small risk of inducing immune suppression to the antigens. Also, 2-week intervals mean the puppy is fully boostered earlier — some clients prefer that for socialization (“safe to go out” date). But that's a convenience argument, not an immunology argument.

What to do: ask your vet directly — “I’ve been reading the AAHA 2022 guidelines and noticed they recommend 3-4 week intervals with a final booster after 16 weeks. Can we use that schedule instead?” Most vets are happy to adjust if asked. If they push back hard without a clinical reason, that’s a flag worth thinking about.

One nuance: in high-risk parvo environments (Southern US shelters, certain rural areas), some vets do use accelerated schedules for population-level reasons. If your vet practices in such an area, that's a defensible position — just confirm there’s a real exposure rationale, not habit.