I've just ordered a GE PGB940SEFSS from AJ Madison, which comes with a warming drawer. The guy at AJ was very nice and seemed very knowledgeable. He told me that the warming drawer has a 72 hour shut-off.
However, when I look at the online manual it seems to indicate that the warming drawer stays on for 3 hours.

This seems like way too little time. I often use my warming drawer all day long when I'm having lots of company and have various courses warming up. Snacks for early arrivals, appetizers, desserts later on, etc.

The manual seems to be kind of generic for gas ranges, not very specific to each model. For instance there's a section about "Convection baking - for models with convection" "Griddles (on some models)" so the information might not apply to every model.

Does anyone have this range with the warming drawer, and does it shut off after 3 hours? If it does, is there a way around it?

Here is a link that might be useful: GE Gas Range with Warming Drawer