Senior in less than 3 years?
Sure, he/she may have "senior" title, but this is nowhere even close to actual senior.
They are señors.
What developer could do in less than 3 years? I'm not talking about highly skilled/talented people
Started at his/her first company, ramped up, got familiar with all the stuff like tools, processes, culture, code base, software development life cycle, learned stuff that he didnt know but needed (e.g tools, libs, frameworks, langs)
It took like 3-6 months, after that he's reasonable contributor to the projects
And now we have 2.5 years left - what you can do in that time?
Participate in one bigger project?
Participate in 2 mid size projects from the beginning to the end?
Participate in 5 small projects from the beginning to the end?
This is your seniority?
You have seen whole software dev. life cycle in 2 mid size projects?
or
You have seen some part of software dev. life cycle in one bigger project?
It is a joke.
Exp != Knowledge, and seniority is about exp and responsibility, so for me it is:
0-3 junior
3-7 mid
7+ senior
and above that you have other fancy things like leaders/principals/etc
Of course, those aren't hard rules, senior with 6 years is ok too, but let's dont be ridiculous with seniors BELOW 3 years.