IP meaning internet protocol number? What about students on a campus network, where there may be hundreds coming from the same IP? And you are managing hundreds of different IPs for your Twitter accounts? How does that work?
I'm not sure about all of the details; I'm sure there are a variety of indicators that go into spam score and once you tip the spam threshold you're banned. So I would guess that students on a school network do things well enough to stay safe, but if you have 1,000 bot accounts on the same IP it's just a matter of time before they're all gone.
So if you want to manage a network of fake accounts I try to use a proxy IP or VPN to connect to each account every time you connect to/with it. (Also clear cookies/cache, spoof the same device, etc.) I'm sure better programmers could work around this by compensating in other ways, but I'm not sure how.