Isn't usually verifying that a PoW solution is correct much less resource intensive than calculating the solution? And if the request format includes the challe

Isn't usually verifying that a PoW solution is correct much less resource intensive than calculating the solution? And if the request format includes the challenge along w/ the solution, the server doesn't need to do any calculations until the user finishes the challenge. (A lot of this is implementation dependant of course, but this is my high level understanding)