So there is no hard and fast rule ,just which kind of gardener you are.
Well O.K. then I only want to plant once and will reverse my rizomes so new growth comes off the inside.Just plant the triangle with more space between new fingers.
I am so happy that I started my 5 year plan and factored in my ageing.I just dont need to dig as many holes anymore but there are more lilies coming as well as daffs .I try to keep replanting at a minimum.