Sine you're leaving it to the AI, which already drops your efficiency in the lavatory and flushes it, what do you care about a few more percent loss?
Because it's basically effective when holding the line, and the AI isn't nearly as bad as people claim it is when presented with a clearly defined front with correctly set objectives?
The AI does a fine job in controlled circumstances, like when fighting in Russia and Asia, and its effectiveness, when given the correct generals at the correct levels of command is astounding. THAT is why radio range is important. The supply usage bonus (at, I believe, Army Group level) alone is worth it to me, and having half your units without that bonus can be a major draw on your supply network and hobble an offensive if infrastructure is poor.