Obviously, YOU will have to determine the length and condition of the runway in front of you, and disregard any runway you decide to leave behind.
When it comes down to reality, FAR 91.13(a) rules here, AND will be the first rule cited in any violation hearing:
No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.
While 91.103 addresses the need to "become familiar with all available information concerning" the airport, runways, and airplane performance, it does not tell you what to do with that information. So, as long as the runway remaining is more than that required by your performance charts/tables AND you don't crash or generate a noise complaint, you won't get a violation. HOWEVER, if ANYTHING goes wrong that generates the interest of the feds, one of the first questions asked will be why you didn't use the ENTIRE available runway.
You could also use (and extend) the advice of AIM 5-1-2.a -- "To maintain IFR proficiency, pilots are urged to practice IFR procedures whenever possible, even when operating VFR." Check out the relevant paragraphs in Part 121 (121.177, .188, .188, .196...). Use the [15%] runway additives for wet runways, etc, even when operating VFR. You can then, at least, show that you understand the rules and attempt to use a reasonable margin -- the same as those used in commercial operations -- in your planning.