I know it sounds a little bit sick but...... heres my ops-ie view....
Personally, (discretion is common sense from a crewing perspective) I find if you respectfully ask the crew if they are happy to exercise discretion and after explaining what the situ is - most of the time the crew are happy to use at least 2 hours (3 hours is pushing it! - we know that!)....
Ultimately and whatever the commercial consequences (and Despite what any other personal perspectives etc.) it is the "Captains" ultimate decision!
Explain more about situ?