> IF they can resist the urge to jump in the pool with the developers, IF!

Honestly, in most intellectual work, the first-level manager having an intermittent toe in the water of the actual work (not focussing there, of course!) I find to be a pretty good sign—if they don’t, my experience is that they either don’t understand it or are overcommitted (usually, too broad a span of control, but sometimes too much pushed down to the first level of management that should be at higher levels), or are inventing no-value work for staff in their slack.

If there's enough work to actually justify a manager, they shouldn't have enough time to do much of anything. Maybe a bug or two that would otherwise go to a junior/weak mid.

I've found this to be a function of the team and the culture to too much of a degree to make a sweeping statement like that. If your team is one you can trust, and your managerial responsibilities align more with what I tend to call a "producer", you can be surprisingly personally productive. But it requires a team that requires guidance rather than motivation and a company that doesn't impose structure from above, and those are admittedly pretty rare.

In some management roles I've had too many reports or too many reports who expected hands-on management and yeah, it becomes a full-time, full-time thing. In others--and, to no surprise, my preferred situation--it's much more of a "first among equals" situation where, yeah, a good chunk of my time is spent in meetings (clustered early in the week when I could) to firewall off my team, but it'd be rare to not be able to carve off a full day or two afternoons for deeper work, whether it's code or architecture or analysis. And in those roles it was usually necessary to write a good bit of code, because I'd been an IC before a manager and had done most of the work--and one of the artifacts of doing more work on it, then, was documentation and making it accessible for the next person.