The idea was floated to use global_default_starttime and global_default_run_length to data-drive what the clock will do if left uninitialized. Though seemingly unneeded, best practices mandate data-driven defaults, rather than magic numbers hidden under the hood. The anticipated usage is that some users may set the default starting time in the gridlabd.conf file.
While we're at it, Jason asked to have the default endtime be NEVER like in V2.x. Bear in mind that this might break a whole bunch of autotests that were just fixed. Recommend splitting this one off until the autotests can be brought back up to current 64E/2X state.
This doesn't seem like something we need to address, as long as the resolution was documented.