We spend a long time (30+ mins) reviewing every single coding challenge we receive. We also use it as the basis of an hour-long interview - probing on the choice of libraries, asking extension questions, etc.
But it's important that you weed out no-hopers at the CV- and phone-screen stage, otherwise you're going to get hundreds of coding challenges and you won't be able to give them due attention.
But it's important that you weed out no-hopers at the CV- and phone-screen stage, otherwise you're going to get hundreds of coding challenges and you won't be able to give them due attention.