I can't run it 24 hours a day for several days for fear my ISP will throttle my bandwidth which I think they have already started doing.
Is this a joke or what?
This said...
You only need the blockchain if you want to run bitcoin-qt and you want to act as a full node, it is not required of course. If you only use the client sometimes, i suggest you another client like Multibit.
Each block is downloaded in some seconds or even less, please check the number of total blocks when the client is running, it should increase, please remember that number and the next time you start the client check if it decreased or not.