Billing clients or projects per hour is like billing lines of code. It's a metric that doesn't correlate to real productivity as much as some people think.
Billings and pay rate basis are parts of a large lie in business.
Revenues are based on customer value, supplier costs, and relative bargaining positions between the two, which moves the balance between the two. The party that can't walk away is the party that loses.
Pay needs to similarly compensate for the provisioning cost of labour, fully accounted.
If you're not paying your employees what theey need to survive and raise families, you're not creating wealth but are extracting liquidity. How you pay isn't terribly significant, though bad bases, such as piecework, are often long-term harmful.
Marginal cost and value are, I'm increasingly convinced, in many ways a distraction. Not entirely, but they confound the matter.
Guy named Smith had a lot to say on this a ways back.
