It's very possible to use a tool for a year or 10 and not be quite familiar with it's operation. You have to actively make the effort to learn new things to learn new things.
Well, I did manage to get through the first year or two (not 40hrs per week but close) with blissful ignorance of what vim was capable of.
Only then did I start picking up new commands beyond the basic insert, append, delete stuff. And even much later did I really grasp vim's concept of text-objects.
Of course, this was absolutely the wrong way to go. Would I have spent more time upfront learning, my productivity wouldn't have sucked as much. But then again, typing usually is not the bottleneck.
What I'm trying to say is: Yes, you can very much get through a year or more of using vim without leveraging it's power. (And you probably will, given how much there is to learn.)
I daresay it's impossible for someone to not use a tool, however complicated, for nearly 2000 hours and not become quite familiar with its operation.
This is also 1/5th of the (disputed) "magic number" of 10,000 hours to master a skill.