Across a large collection of tasks, an idea found while working on one task can be useful for future tasks even if it does not improve performance on the task where it was discovered.

“But if you have a whole large collection of tasks,”

“Sometimes you cracking interesting pieces like a primitive ideas from one task and although it is not improving the performance on the current task you can potentially bring that idea to future tasks and that's actually my own definition of interestingness or open-endedness which is an idea need to be”