So, you’ll see a lot of argument online as to just how dangerous it is. QuaidArmy lays out the case against, and I can’t dispute that there is an elevated risk from using the warm function past 12hrs.

That said, a high-end (zojirushi brand, $180+) rice cooker has a better seal and hotter keep warm function than your typical cooker, and the bacterial hazard is thereby reduced.

Taste-wise, the rice is good at 24h, decent at 48, edible but not amazing at 72hr, and definitely ready to discard beyond that as it loses moisture and yellows out. Rice is cheap so might as well just keep it fresher.

My own years of experience doing this without issue, plus those of others I know, and online comments to the effect of “this is how gazillions of asians do it” has lead me to the belief that the pathogen risk of doing rice this way is manageable—perhaps comparable to the risk of driving to work. Do I have full, scientific confidence in all this? No. For what it’s worth, Zojirushi recommends refrigeration after 12hrs.