I have grown day lilies in shade and poor soil above chalk in France near Paris and in heavy clay in full sun in East Anglia for nearly 20 years each time without splitting them and they have just kept on flowering, thriving on neglect.
i have now planted a 15m 'river' of mixed varieties along the top of a bank, with crocus tommasinus, anaemony blanda, and mostly species tulips to prevent the weeds from the wild, lower side of the bank from intruding onto the higher garden side. It is 3 years old now and works very well. The first year only the yellow fragrant hemerocallis flowered from late summer until the first frosts. Last year, the yellow ones flowered in the spring, followed by the red ones (approx 60 cm high). Which continued all summer. This year the yellow ones flowered in spring, (with a few flowering again now!) and the red ones have just finished and have lots of swollen seed pods. I shall be taking out some of the red ones and replacing them with lighter colours for more impact.
The tulips other than the species are bulbs that had previously been in pots. Not only have they flowered in this border, but the flowers have increased since they were planted there!