Calculate time outside of specified ranges

I want to modify column J so that it only tallies the duration OUTSIDE of the excepted times in rows F5 / F6, H5 / H6 and J5 / J6 ... or discounts the duration entirely if a checkbox or drop down is selected.

ooh ... missed another crucial part ... the only time that counts is the time between B5 and B6 ... for instance if the shift is 8 am to 5 pm and there is a PROJ from 4:45 to 5:05 ... then the time is REALLY 4:45 to 5:00. The way I have it set up both the start time AND the stop time would have to be within the shift in order to count. That's wrong.

Geez I'm even confusing myself at this point.