Most junior partners get “noticed”.
There’s a need every few years to bring in one, or more, new partners to refresh the team.
Usually, VCs recruit extremely successful, but usually still up-and-coming folks informally from their networks as new “junior” partners. Since generating substantial cash-on-cash returns in VC can take 12-14 years (or more), most VCs are looking for partners around 30 years old, plus or minus, for “junior” partner role. So then when you are mid-40s, you’re in your prime, have generated substantial cash-on-cash returns, etc.
The best way to get considered for these roles is to meet as many partners as you know, and just let them know you’re thinking about “the next thing.”
If they have an upcoming spot and they think you’re a candidate … they’ll ask you when you tell them you’re thinking of the next thing.
There are 10,000 candidates for every VC partner position. But it turns out, like any senior job … you never really have a surplus of (x) truly great and (y) available candidates.