What is the role of information about the cost of a developer's hour of work in determining the cost of solving a problem?

Question

Career in IT

Almost everywhere there is a phrase about the cost of an hour of work of a web developer, but what is the true value of this information? How much does this say about how much it will cost to solve a particular problem?
If the developer has already done a similar task, then he retains the best practices and for the next client the solution of the problem will take not 30 hours, but for example, 20-30 minutes, and judging by the cost of an hour, it will cost 700 rubles? Or will another developer spend a week learning, then trial and error, and charge a cost equal to 50 hours of work to solve the problem?

Answer 1

Role in multiplying hours by cost per hour

Answer 2

Consent is the product of non-resistance on both sides. Everything else is marketing.