"They've got 20 years of experience."
Oh? Doing what, specifically? Under what operating conditions?
I find that experience often renders a false positive. Too often, it is calculated across a single axis of time. The way that I view experience is two-dimensional. On the X-axis is time. On the Y-axis is the number of unique operating conditions. Given the same operating conditions, 20 years performing the same function that can be learned in six months is six months of experience. TL;DR: this is the experience fallacy.
The aspect of a startup that I enjoy most is the learning velocity. Startups are self-selecting learning machines where the rate of change in operating conditions is inversely correlated with size. The profile of candidates attracted by this environment is more interested in building the ladder than climbing it. They recognize that without builders, there is nothing to climb.
The consequences of this diverging thought paradigm are why some companies grow exponentially while others grow anemically, if at all. Being embedded in an environment of builders is the single largest contributor to learning. Learning compounds with building. It's an intellectual atomic reaction.
This is why experience needs to be viewed through a lens of skepticism. It's not one-dimensional. Time is a single factor. What were the operating conditions in which someone worked? What was built as a result of their work? Do they know, down to the metal, how it was built? These are the questions that quantify experience for us.
As well it's important to understand what has yet to be accomplished; what has yet to be learned. A significant attribute of experience is acknowledging what you don't know. "Do I know what I'm doing?" is a question I ask myself regularly. I'm ruthlessly honest when answering it. And when the answer is no, I don't view it as a weakness. Instead, I view it as an opportunity to learn. It is an opportunity to build experience.