If you’ve got a big bowl of pistachios, it’s worth avoiding the costly error of putting the shells back into the serving bowl. The more you do that, the harder it is to actually find a useful pistachio going forward. Better to have a discard pile, which means that the chances you’ll get a good one from the big bowl are 100%.
On the other hand, if you and your team are in the habit of putting ideas, “that will never work,” in a permanent pile of discards, you’re almost certainly missing great opportunities. There’s a difference between, “that didn’t work once, under certain conditions,” and, “that will never work.”
Alas, we do the same thing with people. Errors in both directions.
Be careful with your discards.