I've talked with several companies in the past 6-8 months where this tenure-based model of elevating engineers to management positions has broken down quite a b

I've talked with several companies in the past 6-8 months where this tenure-based model of elevating engineers to management positions has broken down quite a bit. What generally happens is, once in management, they end up on a track of being more business-facing and the breadth of their role continues to expand (while reducing hands-on code time) to the point where the organization has to relent and hire from the outside anyhow when the promoted manager finally admits they'd have rather remained hands-on. I try to identify engineers on my team with an interest and early aptitude for management early-on, and mentor in that direction while mentoring those who wish to remain hands-on in the other. I always need a right-hand person to handle the higher-order organizational aspects while I'm away, and likewise, I need a left-hand person to lead the day to day technical execution. So usually I'm not lacking for support while at the same time elevating them to the next level (and without needing to hire someone from the outside).