Sure, if you have the same heat source, in an environment with the same atmospheric conditions, working on a piece of meat similar to what you've cooked many ti

Sure, if you have the same heat source, in an environment with the same atmospheric conditions, working on a piece of meat similar to what you've cooked many times before, you likely don't much need a thermometer, not that it'll hurt. But a thermometer let's you transfer those skills much more easily to environments with varying conditions, It's especially common for professional cooks to be expected to cook in varying conditions.