Sustained profits lead to profitability. But, what does it take to be profitable month after month? Year after year?
If your costs are higher than your revenues, you will never be profitable, no matter how productive you get. Calculating pricing using net profit per hour ensures your overhead costs are covered in each job.
Labor productivity is watched because your profits are totally dependent on the number of hours that a job took. You will soon notice good crews and bad crews; productive field labor and non-productive field labor. This is a training opportunity or a "find another employee" opportunity because a non-productive employee costs you money.
Get your financial statements in order, make sure they're accurate and be strategic with your pricing, and you'll soon be on your way to your most profitable year ever.