What we do is show a sample of the programming on a touchpanel prior to having the system installed, usually just after the project acceptance and during rough wiring. The client hasn't seen the system operate yet, and the touchpanel will seem fine to them at first blush. Present the touchpanel for customer acceptance, and have them sign off on it. From that point forward they understand that changes are extra. I still give them at least one gratis reprogramming because they can make the case that it's hard to understand "how they want it" until the system if operating in front of them. Nonetheless, if you establish up front how the touchpanel will look and behave, and make it clear that significant changes are an extra, this will sharply limit (in my experience) the re-do's to touchpanel programming that might ensue.