I started out cooking on an old ECB with out a thermometer. Didn't have a meat thermometer either. Cooked that way for years. Then moved on to a cheap New Braunfels offset and still didn't have a thermometer. It wasn't until I got an OK Joe Vertical Roasting Oven I ever cooked Q with a thermometer. Using nice accurate thermometers these days almost feels like cheatin'.
OK Joe Longhorn & Original Ok Joe Vertical Roasting Oven hybrid, Char Griller Akorn, Falcon MK V gaseous grill