I’m not sure how unique that is, though. Most companies once you’re in doing technical, your peers will trust you to switch teams or broaden out a little. Re-testing a coworker would come off anywhere between amusing and insulting.

At larger companies I've worked at without central hiring committees it was common to get re-interviewed unless you were vouched for by someone pretty senior.

We would always interview internal candidates for technical abilities at Intel.

I don't doubt that you're required to maintain your own code after you've checked it in for others to use ("pass it off") but have you always designed your own solution or have you had to implement designs by higher ups for some not insignificant percentage of the time?

I've never been given a design doc to implement (though I prefer to code, so sometimes I wish I had). I've always been expected to do the research and figure out the design for myself. Sometimes I ask people to fill in parts of a design doc that I know they'll be implementing. This ensures they are aware of the design, it's correct, I haven't missed some critical details, and they have essentially written the design for their own work.

Occasionally I've had a design review where a higher-up has said "this is why we aren't going to do it that way". I've always been given a reasonable reason (not always one I agree with, but reasonable). I've always been the one to re-write the design in these cases.

not OP, but currently a manager at Google (full disclosure, opinions are my own, company is not involved, etc)

I fully expect that everybody at Google will create the designs for the problems they own, get the designs through peer review, work on implementing these designs, and verify that the solution is solved in process.

What changes with the seniority level is the scope of the designs - a junior may be expected to design their piece of code, only their module, a mid level is expected to design an entire subsystem while delegating individual modules, a senior is expected to design an entire system delegating the subsystems, etc. Of course, it's not so clear cut all the time, but the critical piece we have here is that - Everybody, at all levels, are expected to share expertise, knowledge and acumen in order to help others grow. When you put everything together it creates a nice cycle of constant growth pressure.

Absolutly I will not qualify anybody's work here as "droning", and if someone in my team would feel like that I would invite them to speak up and work together into making it better.

About the quality of people here, what has impressed me most is the uniform high level of competence and niceness. In other companies where I've worked the skills would more-or-less all over the place, but here it's uniform good. I'd rate Googlers consistently in top 20% of the teams where I've worked with before. Also everybody is so very nice, a real pleasure to be around and work together. I still haven't discovered how recruiting selects for this, but everybody constantly passes the airport test my in book.