If you have three Lightning channels, and two of them have plenty of spending capacity, but you want to send a transaction that is larger than the balance in either individual channel… does your node “do the work” for you to make a combined payment from both channels? Would it likewise split out a larger incoming payment to multiple channels, and “fill the first cup before it starts filling the next” 

How does it know to do this, if each channel is opened to a different peer? #asknostr