Search patterns are fascinating. I've been managing Job related PPC campaigns for over a year and it's interesting to see how people's brains work.

Hits decrease in school holidays and when the weather is good. January on the other hand is crazy season. If there is one time when you want your PPC campaign to be working for a job site, it's January when everyone is trying to change their life. Weekends drop right off and Monday morning shoots right back up again.

So - If you've got a limited budget to stick to, it's worth using the "day parting" withing Google Adwords to deal with these fluxes. For example if your budget is £700/week, you might initially set the campaign to run at £100/day 7 days a week, but it would be far more sensible to pause the campaign at the weekends and set the daily budget to £140/day.