No, there's not an out of the box setting on this. Edit rules would still apply so if they had planned materials at the job plan header level for example, that would generate an error (typically, though customers can change the edit rules). But there's nothing to prevent a job plan from being set out of the box.
A global data restriction (or something like that) to make the field read-only is probably what I would do. Or you can add validation via an automation script if you want to throw an error to the user.
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Steven Shull
Naviam
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