About a year after the Swissair 111 crash, I had smoke fumes throughout the cabin and cockpit. Our checklist said to shut off the non essential busses and see if the smoke decreased.
We were headed south out of MIA over the Keys. I immediately shut off the non essential busses with no checklist and declared an emergency and proceeded direct to MIA. I set up an autoland even though MIA doesn't have autoland. After completing the checklists we landed with smoke fumes throughout the airplane. The source was the galley oven. We shut that off instantly. Two weeks later they changed our checklist to what we did. A flight engineer would have done the same thing. We were in a 757 so didn't have that available. Coming out of a 727 makes it hard to not miss an FE.