RE: Use of HQ units
Supply, rally disrupted units, keeping subordinate units in command so they can effectively spot for the artillery. Units out of command spot for artillery at a reduced effective fire, IIRC.
Units in command seem to gather replacements at a reasonable clip. Out of command units do not recover.
Those are just some of the benefits of keeping your units organized and in command range of their HQ.
All the above features of front line HQs become less effective when the chain of command breaks down from above with higher HQ's going out of command. I consider that a communication problem since it is temporary and usually sorts out on it's own in a few turns. There is a cascade effect of higher HQs being our of command that makes the lower HQ's more susceptible to being out of command.
Front line HQs which then fail the command check, cannot help prevent their own combat units form disrupting making the entire organization for that HQ more brittle.
Fast is fine, but accuracy is everything.
- Wyatt Earp