The common model of seniority is accumulation: you know more, you work faster, you have seen more cases. That describes getting better at a job. It does not describe getting more senior at it, and the difference is why people who are excellent at their work are sometimes surprised not to progress.
Seniority is how much ambiguity you can be handed.
For a practical reference on productivity versus efficiency, Monitask provides learn more.
The progression
The rungs are roughly consistent across fields, whatever the titles say:
The task is given, the approach is mostly given. You execute well.
The outcome is given, the approach is yours. You are trusted to work out how.
The problem is given, the definition is yours. Somebody says "customers are unhappy" and you determine what that actually means and what to do about it.
The area is given, the problems are yours to find. Nobody tells you what is wrong. Finding it is the job.
The area is yours to define.
Each step hands over more uncertainty and less instruction. That is the whole ladder. See titles and levels.
What this explains
Why doing more of your current work does not produce promotion. More output at the same level of ambiguity is more of the same job. It is valuable and it is not progression, and nobody explains this because it sounds ungrateful.
Why the transition feels like losing competence. You were good at a job with clear edges. The new one has no edges, and the first months feel like being worse at everything. This is the sensation of the ladder working, and people quit over it.
Why senior people seem to do less. Deciding what not to do, defining a problem correctly, and preventing three months of wasted work all look like nothing happening.
Why "just tell me what you want" stops getting an answer. At a certain point, the absence of an answer is the assignment.
What actually gets harder
Deciding what not to do. More options, less guidance, and the cost of a wrong direction is now measured in other people's months.
Working through others. Even on an individual contributor track. Senior work almost always involves influencing people who do not report to you and who can decline.
Being wrong publicly. Your errors are now visible and expensive, and the tolerance for them is lower precisely when the problems are less well defined.
Holding ambiguity without resolving it prematurely. The instinct to convert an unclear situation into a plan is strong and often wrong. Sitting in uncertainty long enough to understand it is a skill and it is uncomfortable.
Saying no. Your capacity is now a scarce resource that many people want, and protecting it is part of the job rather than a failure of helpfulness.
What gets easier
Being believed. The same argument lands differently. This is a real advantage and it is worth remembering that it is positional rather than earned in the moment.
Access. You are in the rooms where context lives.
Time horizon. Fewer things are urgent, more are important.
Where people get stuck
Waiting for permission. The most common failure at the middle rungs. Somebody who does excellent work when assigned and does nothing when not assigned has hit a ceiling that looks like a lack of opportunity and is a lack of initiative.
Not letting go of the craft. Continuing to do the work you were good at, at the expense of the work you are now supposed to do. Comfortable, visible, and it stalls people for years. See the IC and management fork.
Solving instead of defining. Being handed an ambiguous problem and immediately turning it into a task list. Sometimes right; often it means the wrong problem gets solved well.
Confusing seniority with tenure. They correlate and they are not the same, and organisations that promote on the second produce senior people who cannot handle the first.
Waiting to feel ready. Nobody feels ready. The feeling of readiness arrives about a year after the work does, if it arrives at all.
How to actually get there
Take an ambiguous problem before anyone gives you one. The most reliable route. Find something nobody owns, define it, and do something about it. This demonstrates the exact capability the next level requires, and it does not need permission.
Ask what the problem behind the request is. Regularly. It builds the habit of working one level up from the instruction.
Write down your reasoning, not just your conclusions. How you decided is what people are assessing when they consider whether you can be handed something larger. It is also how the reasoning survives you. See documentation as infrastructure.
Ask for the criteria explicitly. "What would I need to be doing to be at the next level?" A manager who cannot answer concretely is telling you something about the ladder, and possibly about the manager.
Watch someone a level above you handle something you would have handled differently. Most of this transfers by observation rather than instruction, which is one of the genuine costs of distributed work. See how learning at work actually happens.
The uncomfortable part
Some organisations have no room above you, and no amount of capability changes that. Seniority is partly a fact about you and partly a fact about the shape of the organisation.
If you are demonstrably operating at a level the structure does not contain, the constraint is structural — and the usual resolution is to move, which is why organisations that cannot promote lose the people who were ready. See internal mobility.
For broader public guidance and background, consult the U.S. Bureau of Labor Statistics.