Change orders are particularly a touchy subject but IMHO one of the most important tools an installation company needs in doing any kind of an extended install. Of course, you may not be able to collect on all of them, but it allows you to document the job properly and at the end most customers will pay what they owe you if you can present evidence to support the additional charges along with their signature on the change order. I don't charge to move an inwall speaker 2 feet to the left if it doesn't have to be done twice but if it is a custopmer requested change after the fact then they will get charged. If you depend on their memory then you're out of luck a good part of the time. As far as wasted trips I havn't been too successful on the first one but I am usually able to collect additional travel time on many occasions for repeat occurances. Rarely can I get paid for additional down labor time but I'm not really sure I'm entitled to that.