I bill the client if what I’m doing for them is either (a) keeping from working on another clients project (example: driving from my office to their site) or (b

I bill the client if what I’m doing for them is either (a) keeping from working on another clients project (example: driving from my office to their site) or (b) if they wouldn’t expect to dock their own employees for doing the same thing (example: updating software). Even without knowing what you are charging I can tell you aren’t charging enough. :-)