Hello @Kaniz Fatma​ yes it is clear.

Following some tests on my side using a ***** notebook that all it does is importing stuff and sleeping for 15 secs (so nothing to do with spark) I figured that even with a 32 cores driver, the fatigue point is close to 6 concurrent notebooks. Meaning that it's not even a question of available cores per notebook because is close to the fatigue point of a 16 or 8 cores driver.