How Long Do You Cook Tamales?

I cooked them for 45 minutes once they reached 15# of pressure and then let them sit in the pot until they cooled down.  They key is to let them cool off a bit so the masa becomes firmer otherwise they are a bit mushy when they come out if you don't wait.  Mine were done.  I just had to let them settle.  I used a 20 quart and had 1 layer of tamales.
Dp

About 4 hours so make them before 12 pm so you eat them for dinner.

I use my roaster oven and stack them on the rack.  The water level is under the rack.  I steam them for about 2 1/2 to 3 hours

Yes, you can cook them in a slow cooker, but that makes a very small batch.  Yes you need to add maybe an inch of water.  You want to steam the tamales, not boil them.

Yes you can and there great!