What are the disadvantages of on-site job fairs?

To the site, there are many people and companies, so it is difficult to choose the one that suits you. How long does it take to go to the company for an interview or understanding after the on-site interview? I have to print many resumes and send them. Online will be better, you can choose what suits you slowly. The "20 17 Spring Traffic Engineering Talent Recruitment Fair" held by China Engineering Supervision Talent Network was recruited by this network, so you can have a look.