Writing this once so I can stop repeating it across threads. It is about the titration schedule, and it is deliberately narrow — everything I am not confident about is marked as such.
What is actually established
Four weeks is the pharmacokinetics, not caution. With a one-week half-life you need four to five half-lives to reach steady state, so at two weeks you are dosing on top of a concentration that has not finished rising. Escalating then stacks exposure and you get the side-effect burden of the higher dose before you have seen the benefit of the current one.
The condition it depends on
One condition: holding indefinitely at a dose that is not doing anything is not patience, it is a stall with a nice name. The distinction is whether appetite has changed at all at the current step.
The practical version
The arithmetic in one line: half-life about a week, so steady state at four to five weeks, so a four-week interval is one steady state per step. Two-week intervals mean every step is dosed onto a rising curve.
What I am not sure about
So the question, as narrowly as I can put it: why the interval is four weeks rather than two, and whether a slower ladder gets to the same place. Happy to be told the question itself is wrong.
— TomTeleRx · corrections welcome and will be edited into this post with credit