All consoles with memory cards (including Nintendo 64) kept reminding you that it's very important to not turn off the power while it's saving, because this would corrupt the save file.
But for the Nintendo 64 games which had the save feature built into the cartridge, such as Ocarina of Time and Majora's Mask (both using different in-cartridge storage technologies, BTW), there is never any mention that you need to be careful to not turn off the console while saving. It seems to either (former) save instantly, with zero waiting whatsoever, or (latter) it's unclear when exactly it actually does save, especially when playing the Song of Time which plays a long animation where you travel back through time.
What if somebody were to stand next to the console and, while pressing the final button to save in the game, immediately switch off the console's power? Would not this inevitably corrupt the save file? And if so, why isn't there any kind of warning about this, when consoles made before and after the aforementioned games consistently mention how bad it is to turn off the power while saving?
Also, if the save feature in the cartridge is so superior, why didn't they use the same technology for the memory cards as well?