Step 4 is when you become the senior engineer, show up to work in sweatpants and a dirty t-shirt with Crocs, and don't go to meetings anymore unless it's about major architectural decisions, and they can't fire you because you've become an oracle of the company software.
I'd say stage 4 is being the keystone attendee: if you don't go, the whole thing falls apart. Even if you somehow manage to get out of the meeting, it has to get rescheduled because it "needs" your input. The meeting thus becomes inescapable.
Stage 5 is when everyone else realizes you're in stage 4 and begins to cater to your availability and preferences. Obviously this is mostly theoretical.
At the start of your career, you want to be important enough that people will care about your opinions, which means getting invited to meetings where things are discussed.
Stage 2, you've been there long enough and know how things work so you can offer input and help make decisions.
Stage 3 is the point at which people will come to you for input outside of meetings because that's easier. You just want to do your job and generally don't care about decisions anymore unless they bring sweeping changes.