A co-worker of mine described the current state of a certain software company (paraphrased):
It’s no longer a start-up. It’s bigger than that. It’s not a mature company either. It’s somewhere in between. It’s pubescent. It’s gangly, awkward, and clumsy.
I’d say that’s a pretty good description of the phase between start-up and mature company. It’s no longer small, young, and agile, but it isn’t yet old and fixed in its ways. The clumsiness comes from not knowing quite how to operate. It can’t continue to operate in the way that it did (in “start-up mode”) because things no longer fit. But it also doesn’t have down the efficient business processes that come with experience.