Having spent a fair bit of time as a manager of developers, there’s one really simple sign (for me personally) that developers are growing: smiles. Those little smiles that I get when I’m hopping in my car after a day at work, or reading an email, or watching an interaction. Those little “wow, yeah, that’s the behaviour I’m looking for” moments.
Without focus a software engineering team can look and feel like they’re doing great, but not make headway. You can have all the right pieces set up just the right way, but all for naught. No amount of engineering talent, no fantastic working environment, nor great team culture can make up for a lack of focus. It’s that important.