Task shape
GLM 5.2 has the strongest case when the prompt stops being small.
GPT 5.5 may remain a comfortable default for teams that already have stable workflows, prompt libraries, and expectations built around GPT-class models. Familiarity has value. If your average task is short, isolated, and low-risk, changing models may not create enough benefit to justify workflow disruption.
GLM 5.2 becomes more interesting when the task gets wider. Repository-scale review, multi-file implementation, long bug investigations, and agent loops all depend on context continuity. These are the conditions where a long-context coding model can create a different outcome rather than just a different answer.
The fair test is to bring one real task from your own work. Ask both models to solve it with the same constraints. Then compare edit distance, correctness, context retention, and whether the output reduces human review.