In my operational team, I'm following a third model, inspired by german trade workers. You have juniors, journeymen and masters. Juniors are generally clueless and need to be told what to do, specifically. This is very much the level of "Here are 28 marks that needs bolts placed in concrete, make it so, I can explain why". Journeymen should be figuring out a plan how to solve a project and challenge it with the master to see if it fits the quality requirements of the master.

And practically, you can have one or two journeymen per master. However, these 2-3 people can in turn support 3-4 more juniors to supply useful work.

This also establishes a fairly natural growth of a person within the company. First you do standard things as told. Then you start doing projects that mostly follow a standard that has worked in the past. And then you start standardizing projects.