What did James Watt's introduction of the separate condenser principally achieve for the steam engine?

Answer

Massive fuel savings by preventing cylinder cooling between strokes

By introducing a separate condenser, Watt ensured the main cylinder did not have to cool down to match the external atmosphere before every power stroke, leading to significantly lower fuel consumption.

What did James Watt's introduction of the separate condenser principally achieve for the steam engine?
inventionmachinepoweradvantagesteam engine