You should be charging more than 100$ for an extra 5 hours of work but that’s my opinion.
This is an old invoice from Tiny Invoice App of an ME gig I did. All companies are different but 10 hours is standard OT to 12-14 double time after that.
Each company is also different how they want their invoices. So there is no specific standard.
depends on the labor coordinator. But generally no if they say half day you are only getting paid that unless you go past 5 hours then it’s a full day.
You rent me by the day, plus overtime and per diem and transportation if out of town. If a local gig and known in advance, I might do a half day rate IF it means I can sell the other half day to another client. If the half day blocks me from other work, I want a full day rate.
I'm a whore, you pay for all my time. And no, I don't kiss.