The issue is, if you Know you can assign that the OT is direct to any specific job, or if the Work Day just ran late.

For this: "The challenge is that any overtime the employee is entitled to falls into the last job that she posts."

Stop using a Multiplier item for OT. Set up the Half Rate as a separate Payroll Compensation item. Use it, like this:

Timesheet entry, Service item = Laborer, Payroll item = Hourly pay, 10 hours, Smith. Billable or not. Next line, for the same date, Service item = Laborer, OT Payroll item = set for half-rate Hourly pay, 2 hours, Smith. Billable or not. Then, Jones job, with or without OT as its own entry.

Now you see Smith: 10 hours at full rate + 2 hours at half-rate. That = 11 hours' of $, the same math as "8 + (2 x 1.5)."

And the reason I like to do this is not just Job Tracking, but also, my Worker Comp reporting wants only Base Rate for all hours. I exclude OT for WC, so that means I am tracking it as a Shift Differential concept.