Also, few people care about your time, if you're out of town with work, have other work that has to take a priority, or for any reason cannot meet a deadline without working 15+ hours on a variety of matters for a few days.
Depends on how you respond, and this is something you have to learn very early on (though I understand if you're not willing to stand your ground as a summer): You have to learn to say "No, I can't do it by the deadline you want."
There will be times when you already have projects to do by a certain deadline, and someone calls you asking you to do something by a deadline that's incompatible with the first project. Don't mention the first project, hoping that the associate will connect the dots (either they purposefully won't, or they have aspergers, or they just can't connect the dots because they're dumb). Be clear: "I have another project that I am already working on and that I have to complete on a shorter deadline, and I cannot do this by the deadline you're asking for."
Learning how to do this will save your ass both in terms of hours and in terms of the quality of your work (i.e., if you tried doing both projects, you'll just do a shitty job on both).
When I first started working, I was asked to do a ton of projects at ridiculous hours and with incompatibilities with my other projects and their deadlines. I frequently mentioned these facts, but was met with silence (i.e., "so... you're still going to do it, right?"). When I bitched about it to my fellow classmates, I'd just hear incredulity that I didn't just say "no." When I finally had the balls to tell an associate that I just can't do it, he said "oh don't worry about it. I'll handle it." And since then, it's been fine (even under the most demanding senior associates, no less).
And if an associate can't take that response, and you've informed him or her that you won't make the deadline, your ass is covered. If the associate complains to the partner, 7 times out of 10, the associate will look like a person who can't lead a project. Just looks bad on that person. 3 times out of 10 it could end up reflecting bad on you, in which case work for a different partner or you chose the wrong law firm and start thinking about looking for another job (and I know that sounds harsh, but really you'll be thanking yourself in the long run).