RE: Why does _no_or_expansion affect Execute time rather than Parse time?

Probably because the CBO optimization is being performed in the Execute phase rather than the Parse due to bind variable peeking.  

From Metalink Note 199273.1:  

"Certain phases may be repositioned dependant on the query submitted. Oracle may combine steps or defer them to a later stage. For example, if bind variable 'peeking' is in operation, then the optimizer needs to use the first 'bound' value to determine the execution plan for the query. This means that optimization will actually occur in the EXECUTE phase as this is the first time that any bind variable values are available. "  

Regards,
Brandon

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