It can get overwhelming to manage multiple budgets across many campaigns. This is especially true when certain campaigns always hit their daily budget and others don’t. Factor in news events or promotions and that can drive up search results. Sometimes the day of the week will make an impact and you’ll find yourself rearranging each campaigns budget on a daily basis. The good news is Google Adwords just recently announced a new option for managing budgets like this called Shared Budgets.
Shared Budgets allows you to automatically move leftover budget to campaigns that are near their daily limit. If you identify which campaigns usually near their daily limit, you can opt them into the Shared Budget option found under "Shared Libraries".
This is a great option if, for example, your Remarketing campaign hits its daily budget consistently on the weekends. By implementing the Shared Budget option and identifying other campaigns that the Shared Budget can take from, you’ll eliminate the likelihood of your campaigns going dark for a few hours each night.