Loyal readers know that I am a strong proponent of the hearing brief, which is filed into the record ahead of a Social Security disability hearing to assist the judge in the evaluation of the claim. Sometimes a post hearing memorandum is also called for.
In my experience, a post hearing memorandum is needed when there has been vocational expert (VE) testimony at the hearing, and the VE identified available jobs in response to the judge's hypothetical questions. After 3-4 hypotheticals from the judge, and cross-examination by the claimant's representative, the step 5 analysis can be muddled. A post hearing memorandum can help to clarify.
Social Security Ruling 96-9p, footnote 8 states in part: "Whenever a VE is used, the individual has the right to review and respond to the VE evidence prior to the issuance of a decision." So a quick post hearing memorandum on the topic of the VE testimony is entirely appropriate.
It may be that the judge has already made up her mind by the end of the hearing. But maybe not. You have to assume that the judge is still considering the matter, and that a short post hearing memorandum will be helpful for your claimant.