The way I’ve handled this “delay problem” – in my fixed-bid agreement – is instead of a “penalty,” I say the agreement is valid for 90-days. If the project isn’t completed by then, the terms are renegotiated. While this isn’t actually used as a “threat”, it’s a nice incentive or motivator for them to keep the energy on high.
Typically, I’ve found unmonitored client delays increase the project time-to-completion by double or worse. If clients had the foresight of compiling and proofing the photos and copy before beginning the project, it’d be completed in short order. This is pretty common so I frequently have to use good old “patience” to finish and get paid. Since I’ve accepted that tolerating and quelling client panic and crisis are part of my job description –and what I get paid for handling, it helps reduce the ulcer. The unpredictable is pretty predictable.
So there are internal and external things we can do to maintain our sanity.