In response more to the original post than some of the comments.
There is a reason to increase the dose to or towards the standard maximum dose, that is strongly supported by the scientific evidence.
Most people taking these medications have significant problems with obesity, this does not apply as much to bodybuilders taking it or those who are younger than 40 or 50 or those who are only overweight. But the people with longstanding significant obesity , are most of the time at significant risk for cardiovascular disease, partly as obesity itself is a significant risk factor and also as high blood pressure, impaired glucose tolerance or diabetes, high cholesterol levels and lower levels of exercise, are strongly associated with obesity and the development of cardiovascular disease and stroke.
GLP medications ( less/not proven for retatrutide at this point ) reduce the chances of heart attack, stroke, heart failure , cardiovascular caused death, and death from all causes. As well as reduced blood pressure, reduced blood sugar and reduced cholesterol levels. Given that these are the commonest causes of death and disability as people age, this effect from GLP medications increases the chances of surviving in good health as you age. The doses of semaglutide and tirzepatide that have been proven to have these effects are the doses used in the trials, 2.4mg or lower if not tolerated for semaglutide, and 15mg for tirzepatide. The effect on improving these outcomes is partly due to the weight loss but the reductions in these levels and events is independent of weight loss, so the chances of these things happening is still reduced even if not much weight loss occurs.
GLP medications may also reduce the risks of developing alzheimer's disease, although recent studies suggest this may not be true, but there are more trials still underway. They also reduce the risks of developing quite a large number of cancers, including the most common ones, but may or may not increase the risks of thyroid and kidney cancer.
Lower doses of GLP medications will still have beneficial effects, but it is reasonable to assume that lower doses will have lesser effects. Demonstrating these effects requires large numbers of patients and long studies, and are therefore very expensive, so it is unlikely studies will be done at lower doses to prove this one way or another.
TLDR Taking GLP medications long term reduce the chances of most of the bad things that can happen to you or kill you as you get older, there is no reason to believe that lower doses are equally effective at doing this.
Increasing doses slowly is generally a good idea, and probably more important when it is being done without medical supervision, which applies to a lot of the people on this forum, but especially for older persons with significant obesity there are good reasons to increase the dose to the standard maximum dose.