Let me try this example:

You and I form a partnership to find, buy and flip one house.

We both "contribute" our labor to making this project profitable.

Our labor is not an expense to the project. It is going to be one reason the project sells for more than our cost to buy it and to buy the materials.

That is not a Valuation data entry component. It's "invested" and intangible as Time.

Because otherwise, why could you not add a Bazillion $ to our basis and reduce our capital gain or profit?

That's why the IRS doesn't allow you to arbitrarily value these types of things. It has to be Actual Cost Incurred.

Go back to the example of Corporate Work and Payroll.

I pay you for that work. Now we have a Cost. A real, known, cost. Until payroll, there is no Cost for that labor.

Meanwhile, I make the sale to the customer. And now I can do the math of Profit for this job. And next time, I might set that contract for services Higher. That's analysis and management.