I get there is an efficiency factor but it doesn’t take more time at home to par boil before frying, it’s just reversing the order. Instead of frying then steaming, you steam then fry and get a much crispier skin on it, so why is this never recommended?
I’ve done both and fry-then-steam is not as sticky, and the water deglazes the pan, if you cook them with anything.
Pierogi though? Boil then fry, they stick like the dickens either way, my husband is the one who makes them - always with kielbasa and sautees them in the sausage pan after boiling them.