Maybe this:

=(NETWORKDAYS([@Created],[@[Completed Date]],'Do NOT DELETE Time Frames'!N$2:N$12)-1+([@[Completed Date]]-INT([@[Completed Date]]))-([@Created]-INT([@Created]))

{or for easier to read: =(NETWORKDAYS(A2,B2,'Dates to Exclude'!$A$2:$A$1000)-1)+(B2-INT(B2))-(A2-INT(A2)) }

And format cell as [h]:mm