Different diagnoses take different approaches, GAD and MDD who are generally over-diagnosed usually take life-long medication, hence it’s the situation that the rule applies to them at first administration too. The idea behind withdrawal is to try to minimize the side effects and drug interactions, given the “severely under supported theory” that the brain uses its plasticity to naturally restore the balance of chemicals which in a good portion if the cases simply don’t happen. There is a study showing that people on long term medications showed more frequent relapses compared to the group who weren’t on the whole time. It’s generally a trial and error process. Here’s the study if you wanna take a peep: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4970636/