Answering the narrow version, because the broad one does not have a single answer. Quarterly for the first year is convention rather than evidence, and it is defensible for a simple reason: it is roughly the interval over which HbA1c becomes informative again, since it reflects about three months of glycaemia. After the first year, and once doses are stable, annual is reasonable unless something specific is being followed.

LabKate said:

Quarterly for the first year is convention rather than evidence, and it is defensible for a simple reason: it is roughly the interval over which HbA1c…

LabKate has the substance of this right. The condition it depends on is worth stating. One addition: if the lab changes analytical platform between your draws, the comparison breaks and nobody tells you. It is worth asking when a value moves inexplicably.

Dr.ObesityMed said:

ALT was mildly raised at baseline, normalised at month five, and I now have no idea whether anything happened to the fibrosis that actually matters.

Agreed, and reference ranges are laboratory-specific. Comparing your number to somebody else's range, or to a screenshot from another country, is how people convince themselves something is wrong.

That is the short version; the long version is somebody else's post.

Clinical perspective, offered as context rather than as advice.

Liver ultrasound comparison for liver and MASH: my hepatologist ordered serial ultrasounds to track NAFLD regression.

Baseline: "Moderate hepatic steatosis, liver span 17.2cm, echogenic texture consistent with fat infiltration"
Month 8: "Mild steatosis, liver span 15.8cm, improved echogenicity"
Month 14: "Minimal to no steatosis, normal liver span 14.5cm, normal echotexture"

My liver literally shrank and de-fattened. The ultrasound tech said she's seen this pattern increasingly in GLP-1 patients and it's remarkable how consistently the fatty liver resolves.