Mentorship
Juniors are not a cost centre
The industry stopped hiring juniors and called it efficiency. Here is what that actually costs, and how we staff differently.
Marcus Okonjo · · 6 min read
There is a comfortable story going around: AI tooling has made junior engineers redundant, so the sensible move is to hire only seniors. It is comfortable because it converts a short-term budget decision into a strategic-sounding one. It is also wrong, and expensively so.
Where seniors come from
Every senior engineer you would like to hire was made by a team that took a risk on them. If the whole industry stops taking that risk simultaneously, the pipeline does not narrow gradually — it empties, about four years later, and there is nothing you can do about it at that point except pay more for the survivors.
What mentoring does to a senior
The argument we find more persuasive is selfish. Explaining a design to someone who will ask why is the cheapest architectural review available. Our senior engineers write clearer code when they know an apprentice will read it, and they catch their own bad decisions mid-sentence surprisingly often.
- Documentation gets written, because someone will actually use it.
- Tacit knowledge stops living in one person’s head.
- Onboarding time drops for everyone, not just apprentices.
- Retention improves — people stay where they are visibly growing.
How we staff it
Every Nexa pod pairs senior engineers with developers from our mentorship track, at a capped ratio of one mentor to four. Mentoring hours are paid and count toward delivery expectations rather than sitting on top of them. Clients get throughput at a sustainable rate; apprentices get real work with real review; seniors get better at their jobs. Nobody is doing anyone a favour.
The programme is paid from day one. Unpaid apprenticeships select for people who can afford to work for free, which is a filter for privilege rather than talent, and we would rather have the talent.