CHECK_
The system property that switches checkInvariants on for every guide path built in this JVM: -Dksl.guidedpath.checkInvariants=true.
It exists because continuous checking is worth most exactly where it is least likely to be asked for -- every model in a test suite, including the ones written after whoever decided to check has stopped looking. Setting one flag on the command line covers models that do not exist yet, which no amount of editing existing tests can do.