Yeast

[Casketmaker]

2) You are starting your batch with billions of more yeast than if you pitch the normal amount. Your beverage will ferment much faster and will finish sooner.

True it will ferment faster but this can also cause an off taste. Fermenting too fast or too slow will affect the taste of the wine. The best reason to reuse the yeast is in the case of mead making. Pitching dry yeast (without yeast energizer) may not always make the fermentation start on a batch of mead but if you use the sediment from a previous batch of white wine (apple or grape) the mead will start fast and will come out good.