Accepted answer
2.4 mg a week is 0.343 mg a day averaged out and 125 mg over a year — but "defensible" is not a property of the number, it is a property of where the number came from. A maintenance dose is defensible when a trial randomised people to it and reported what happened, and indefensible when it was arrived at by interpolation between two doses that were studied. So the question to ask of 2.4 mg is which arm it corresponds to: if a programme ran 2.4 mg as a maintenance level, there is an efficacy figure, a tolerability figure and a discontinuation rate attached to it. If it sits between two studied levels, everything said about it is extrapolation, and the burden of that is on whoever proposed it. The other half of the arithmetic is supply: at 2.4 mg a week a 10 mg vial is 4.17 weeks and you will need about 13 of them a year, which is worth knowing before the dose is settled rather than after. Maintenance doses are set by a prescriber against an individual; nothing here is medical advice.
Start with what is being maintained — weight, glycaemia or both — because they have different dose-response curves.
Weight is a noisy signal. A rolling four-week average is the instrument; single weigh-ins after a dose reduction will show nothing interpretable.
Gastrointestinal tolerability generally improves on a reduced dose, which is a genuine quality-of-life argument for the search rather than only a cost one.
The counter-regulatory hormonal response to weight loss persists for at least a year after the loss, which is the physiological reason maintenance needs something rather than nothing.
Nothing here is medical advice, and research-use compounds are not approved for human use.
The withdrawal trials answer stopping, not reducing. Different questions.