ok, I'll bite.
I see it as imperative to knowing your true costs to getting out into the field to do some of the work, repairing items here and there, etc. Without knowing how long things actually take, you are the mercy of sandbaggers, shady mechanical plays, etc. and that's true whether you are a solo operator or have a thousand employees. That is a part of accountability.
That being said, knowing your costs, your market, your equipment and all the various aspects to keeping production going is completely useless if you aren't selling and selling to maximize everything at your disposal. That's how you grow, that's how everything gets paid for and THAT has to be priority number one for any owner, whether you think of sales in a leisure-suit-wearing-used-car-guy kind of way or not. No selling equals no customer equals no revenue equals no company. If you are a sell first priority maker, you may not even do production (think subcontracting where you still are being paid a percentage).
There are no magic numbers that make it all happen. You cover your costs (all of them..and they WILL be different than every single other LCO) and charge more to make a profit, regardless of service. Customers will be looking for the value in your offering and only selling will make that happen.
Working in the office with spreadsheets endlessly isn't going to get you there.