Master planning is such a parameter and decision driven feature involving lot's of setup and manual configuration.
MS recently released a wizard in Dynamics 365 Supply Chain which can make this process simpler.
Things which the wizard helps are:
1) Determining number of threads
2) Planning scope
3) Scheduling options between high level and detail level
Coverage settings plays a significant role on Master planning
https://docs.microsoft.com/en-us/dynamics365/supply-chain/master-planning/coverage-settings
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