Am very much of a colour (sunshine) perennial gardener myself, but love your beds.
For gardening to a certain level, at least with our growing conditions:
I'm sure perennial gardening is a lot more of a challenge than annual gardening.
Would say that here the average mixed perennial bed goes through perhaps a five year cycle, being best in the second/third year after planting.
By the fifth year, it's time to pull it apart and start again.
There are some, typically deep-rooted, perennials that it's not good to disturb and that it may be best to work around.
Barring this, you just end up with a small variety of particularly hardy plants (significance for me, a small amount of colour through the growing season).
You can look at individual perennials separately (e.g. divide every three, or whatever, years), but if there's a lot of different perennials in a bed, I find I need to deal with whole beds, or sections of whole beds, at the same time.
It's amazing how much work, expense and knowledge mixed perennial gardening can be, though keeping on top of things during the five years, makes it very much easier.
And besides, there's a lot of enjoyment in both the challenge and the product.
