Isn't this counter to what RAD/AGILE what have you? Yesterday a look at solution a for problem y and it turns out that was a dead end so we wont do that any mo

Isn't this counter to what RAD/AGILE what have you? Yesterday a look at solution a for problem y and it turns out that was a dead end so we wont do that any more. Today Looking at solution b for y or can we solve y by doing something else