I have mostly different varieties of Painted ferns and have lost way less since not cutting back till I see the new growth starting . Also have not lost a Hellebore since doing them the same way.
With the more common Echinacea it does not seem to matter as much but with the more sensitive hybrids it helps to protect the crowns of the plants. But most important for them is being in an area that does not retain water in the Winter.
