At startups, senior engineers only need light supervision.
Their time should be spent listening to customers, directors, and other stakeholders to check if they're sorely missing things. They should keep lines of communication open and be proactive.
One thing we don't see often enough is the "Principle Software Engineer" role in startups.
At most startups, it's an open office floor plan. The data analysts, sales person, and marketer would come up to me with a request for something that was actually detrimental to their doing their job, but it wasn't getting focused on in our sprints.
At Boostable (W14), I was handling all server / e-commerce / front-end issues, plus setting up systems for marketing and sales needs that wouldn't have otherwise been done. And it brought substantial value to the company, for low hanging fruit a manager would have kept kicking the can down the road.
The issue is, these proactive things were never recognized or appreciated the way I think they should have been. Heh. It's as if it the work being unofficial made it less valued, when the way I saw it, it was shared success.
If a programmer is impactful and setting the best practices for the team, they can report directly to VP/CTO. Less supervision. Mentor fellow employees.