Do you have a source? Here is what I found.

At ExpressJet we offer duty/trip rig pay on top of pay for time in the air.

Our ERJ trip rigs are:
4 day trip = Minimum 15 hours of pay
3.75 hours of min day pay for an off day pick up
3 hours of min day pay for a calendar day layover on a trip
2 hours of min day pay for a flying day during a trip

Our CRJ duty rigs are:
Paid 1 minute for every 2 minutes of work up to 12 hours (1:2)
Paid 1 minute for every 1 minute of work after 12 hours (1:1)
3.87 hours of min day pay