"Lowest effective dose" is a general principle in prescribing: use the smallest amount of a medication that reliably achieves the treatment goal, because side effects usually scale with dose while benefits often plateau. It is the reason GLP-1 medications are titrated up in steps rather than started at full strength, and the reason many people stop climbing before the top dose on the label.
For GLP-1s, the goal might be blood sugar control, a satisfactory pace of weight loss, or holding weight steady in maintenance. If that is achieved at 1 mg of semaglutide or 5 mg of tirzepatide with manageable side effects, there is often no clinical reason to go higher — and the ADA's guidance explicitly makes this point. Staying at a lower dose that works is a legitimate outcome, not a compromise. See what "maintenance dose" actually means and why some people stay on a lower maintenance dose.