If you replace “mV” with “mA” you are mathematically correct. You can add up the current requirements (mA) of all the pedals and that has to be less than the current rating of The power supply. The catch is that many pedals don’t turn off when bypassed, so they are still drawing current unless physically unplugged. Overloading the power supply may over time cause the power supply to fail or it may cause a condition that damages the pedals, depending on how things are designed. It’s best to get a big enough power supply or divide the pedals onto more power supplies. Dividing has the advantage of having a spare power supply On hand if one fails.