You can have many vertical levels. It’s the role design that you want to solve for. The flattening is a side effect. Managers hiring more managers because they don’t have capacity to manage all of their subordinates is a cancer that grows. Do it two times and you now have three managers that all view themselves as managing the same individual contractor at different levels of specificity. And inevitably one guy in the middle becomes nothing but a gatekeeper for talking to the bigger boss. It’s countercultural but productive for people’s scope of work to go down every now and then.

The number of direct reports should scale with the level of tactical involvement. Call center employees -> huge team. Dev work -> small team.

Team of tech leads each running their own project and teams independently? Probably pretty darn big team. You can manage a lot of tech team leads so long as you do not go into the weeds.

As discussed elsewhere, the operational sides of the US military are a pretty good example of effective organization and delegation. This is in part because the critical real time, limited communication nature of military operations forcing the organization to adopt a structure that cuts out the wasteful managerial cruft you often see in the business world.

Russia operates its military more like a U.S. corporation and you can see how it fails them daily.