I also used to plan with more expensive models like you did, but now I just do planning with DeepSeek too and don't see much difference. I use the omp plan mode and iterate on the text until I'm happy with it. Then clear context, give the plan to DeepSeek again for implementation.
If it's mission-critical code, do a security review with GLM 5.3.
Otherwise go manually through the code and ask for changes if needed.
