To have a successful design system, you need to make a continuous effort to invest resources into it. I like to compare this to working out.
You can work out intensely for 3 months and see some gains, but once you stop working out, those will slowly fade away. If you continue to work out, even if its less often than the initial investment, you’ll see yourself maintaining your fitness level at a much higher rate than if you stopped completely.
If you invest once in a design system (say, 3 months of overhauling it) but neglect to keep it up, you’ll face the same situation. You’ll see immediate impact, but that impact will fade as it gets out of sync with new designs and you’ll end up with strange, floating bits of code that nobody is using. Your engineers will stop using it as the patterns become outdated, and then you’ll find yourself in for another round of large investment (while dreading going through the process since its fallen so far out of shape).
Great post from Una on what it takes to build a successful (and lasting) design system. I'm in the process of planning a big design system that I'll be working on the coming next months so this article was a goldmine for me.
There are a bunch of posts out there that are talking about all the benefits of having a design system (and they are all right of course). But just like Una's analogy with working out - working out is great for you, there's no arguing that. The hard part is maintaining that fitness, sorry design system.