>>21488524Preparing potatoes does not take 30 minutes. You skin and cut them up in 3-4 minutes (for a large serving of pierogi ruskie you need only a couple of big potatoes), and then leave them to boil for 20 minutes, during the time which you can do whatever else.
It depends on the filling but for pierogi ruskie the filling is not really a lot of time, just boil potatoes until soft and brown some onion, then mash it all together.
Most of the time is spent on filling them especially if you are inexperienced or do a large batch (unlike everything else time spent filling and forming the pierogi scales linearly with the amount ). For 1 or 2 people, you can relatively easily do it in around 30-45 minutes, including the resting of the dough.
If you do it for more people, then you can save a lot of time because making the filling and making the dough are completely independent tasks so you can do them at the same time, albeit the dough does not take much time to do, maybe 10-15 minutes mixing and kneading plus some rest time.