That’s a great point you make. I think their are a few factors at work here:

Personal Maturity

There are plenty of good books and resources written about this one - such as “The Myth of 9-to-5″. As this book points out, personal maturity is somewhat independent of age, and moreso independent of intellectual ability.

Personal maturity is one of the determinants of how much people will resist change (not one specific change, which might be resisted for other reasons, but more generally any change). With respect to our progression to a more Agile organisation, we have people at various stages of a continuum.

Professional Experience

Professional experience is a key determinant of how well we can do things such as estimate the time it will take to complete tasks (in simple terms, more experience provides more opportunities for “like-for-like” comparisons) - along with the obvious benefit of knowing better ways to code solutions.

This is one of the main reasons why I am very keen on fostering a culture supporting life-long learning.

As a rough guide, experience can be measured in years of working - but even this can be a little misleading, as many years stuck in a job providing no diversity does not deliver as much value as perhaps even fewer years in a more diverse environment(s).

What is “Junior”?

Hence, “Junior” is (in my view) a combination of maturity level, experience level and other factors I don’t have time to go into right now.

Of course we can (and will persist to) continue the development of our junior team - in my judgement this will be aided considerably by adding to our team people more senior and hence able to accelerate this development by acting as coach (amongst their other roles).