wouldn't poeple just flag everything as their fav 5 and put high numbers of hours not actually spent on the application? unless the system can track all a candidates applications, this seems moot, and if it did track all that yuk no thank you, i don't need more tracking in my life to solve a problem we created artificially. Plus it is probably easy to game for anyone with a minimum of programming skills...
The thought process was tracking all candidates (not having a user-submitted number). That tracking is already happening for most marketing analytics. I'm surprised I haven't seen it show up on the job application side.
As for the fave 5 idea - I don't see an easy way to game this if it's tied to a single user account. You would only be seen as prioritizing the company to the employer if you're actively prioritizing them. Most people are applying to way more than 5 companies simultaneously and don't know where their application stands for the company. It would be too risky to try and rotate it continuously.