Well, this post is mostly about the flip side of campus interviews and how you should deal with them mentally.
Many companies play hard to get with their eligibility criterion. They may never give you a chance to sit for aptitude tests if you're not the right discipline. They may never correct your papers if your CGPA isn't high enough. They may just toss you out after a few rounds of reckless interviews if you're not the right discipline. This is besides the regular process based on talent, discipline and CGPA. So don't get bogged down by these: They aren't worth your time or emotions.
We need to realize a few facts here. The HR department is just whacked up, made up of mostly non-techies who can place safe bets on a person with a good CGPA and discipline. They are answerable for your productivity after you join the company. So if they were hiring you otherwise, they might get fired; According to them, they are doing a very good job. But here's the catch: they also don't realize the significance of job profiles and how good many people actually fit for one or two job profiles. Like, if they are going to test a person for his competence in many areas, there are high chances he isn't going to work on all of them at the same time. He might be shifting to another project in the company, but they don't realize that a lot of practical learning comes with the job, not with the degree. Also, if your CGPA is low, they just assume you're insincere. But that's not an excuse to not give the guy a fighting chance in a technical interview.
The next problem is with traveling with a company all the way to some distant university to hold these things. Although they are going to get paid for it and all, travel is very hectic and their project schedules are way off. They would mostly be focussed on coming back and getting things right on track. They just want to finish it off early, and concentrate on a few number of 'quality' students.
If you're thinking that you've ruined your entire university life because you didn't get a dream job or any job at all, think again. There is a lot of opportunity given in your life to work hard and come up. There will be people undermining you all the time; You need to learn to fight back and give things your best shot at some point of time. Tension has an immense effect on productivity. You must never let it get to you.
Life isn't some sort of race. Someone else you know may get ahead and you might feel bad that you couldn't do it. But not that they haven't any problems. Even the ones who deserve to get ahead may end up dying prematurely or catching some illness, sometimes making you wonder why life is so unfair to even those who deserve better. So are you any better or happier? It's not a happy thing to laugh about, but a good consolation to not feel any worse.
Life isn't unfair, it's just our way of looking at it. We do know that all of us will get a hard cut in our life and die; That doesn't make it any harder than it is. And we needn't get depressed about it either. Knowing that it will be hard at the end, why not learn to enjoy the trail while it lasts?