Everyone has a lottery system, except for a very few schools. It is a mistake not to do a lottery system. The employers will get their people, so there is no reason to worry about them.
From a student's standpoint (which is what I was discussing), it makes a big difference.
If you do a lottery, like the one people have described (not the "random thing people were talking about earlier), everything works out as hoped. The student meets with their counselor and talks through firms they will apply to. Your counselor will undoubtely tell you to bid consesrvatively, meaning on firms they know are obtainable. This is a mistake, because getting a top Vault firm job is very very easy. There are some elite shops (small firms), but they don't show up highly ranked on Vault. For instance, Jenner & Block (DC Office) is very hard to get. However, Skadden (highly ranked) is unbelievably easy to get a job at. Vault doesn't tell you this, because Vault is basically useless, but that is for another time.
I digress...with the lottery, almost all the students will have the same number of interviews. Out of about 50 bids, they will probably get 30-35 interviews.
Now, in a preselect (which I stand by my word is dumb) system, the top students don't know what to expect, so they use all their bids. There are not 50 top firms in their locale(s) of interest, so they bid on ALL the firms. Everyone gets excited and uses all their bids. Why wouldn't you? Now the top of the class gets like 40 interviews, and the bottom of the class (bottom 1/4) gets none. This is how it works at a top school that does pre-screening. At lower ranked schools, firms allocate less spots overall for interviews, so a higher and higher proportion of the class receives a limited number of interviews in comparison to the top of the class.
For instance, at Northwestern, Kirkland & Ellis will allow 80 to 100 students to interview with them. Not even 100 students have an interest in the firm, so you are guaranteed an interview slot with them no matter where you rank them in your bidding preferences.
At say a lower ranked school (say DePaul), Kirkland & Ellis interviews say 40 people, so they interview the very top 40 people. Another top Chicago firm, a little smaller than Kirkland & Ellis, only interviews maybe 20 people. They interview the very top 20 people. Thus, the same people get interviews over and over.
This won't happen to the same extent at a UVA, because firms will allocate so many spots, that there will be enough to go around. Still the bottom of the class will see significantly less interviews. Thus, if your grades are not up to par, you only have 10 chances to impress, instead of 30, if you are in the bottom of the class.
Furthermore, the top of the class does not suffer in a lottery system, because they are going to get the jobs no matter what. They don't need 30 or 40 interviews, but I guarantee they are going to bid on them. They only need 20 interviews to obtain 10-15 callbacks.