rpupkin and Capitol_Idea has it right, here. Not being in your office isn't a problem until it's a problem, but when it is one, you're not given a pass just because it's never been an issue before.
Just some additional comments before I leave the office at 7pm instead of sticking around in case a partner needs me.
why would a partner waste their time to physically come to your office? they would call you and tell you to come up. its on the associate to go to the partners office.
Not everyone is in this boat as people already mentioned. My office is RIGHT NEXT to one of the partner's offices, and we happen to have a lot of cases we work on together. We walk 10 steps to stop by each others' offices all the damn time to talk about cases (and occasionally to shoot the shit, but that usually happens as part of talking about cases). Of course, my office is also on the entire opposite side of another partner's office, so while I have some cases with them too I don't see them anywhere near as often. The other thing has to do with phones, every firm does it differently I'm sure, but sometimes the partners don't have our cell numbers handy for whatever reason so they call the office when they're in court and need something. So even without dropping by, if they call your office phone and you aren't there, that's a problem, too.
i wouldnt be proud that some shithead partner likes you
Partners liking an associate is how that associate stays at the firm and gets work rather than having to hunt around for shit doc review projects, how the associate gets market or above-market bonuses at some firms, and potentially becomes partner years down the road. Of course, if you don't give a fuck about any of that and you're just chilling at the firm for 2 years for big ass paychecks and skipping right out of there after that, well then, of course you also won't give a fuck if you're not in the office when a partner needs to talk to you.