Sims with high free will don't take preventative measures when it comes to their needs like we are used to doing. They usually act only when a need is quite low. This do result in Sims living their lives inefficiently when left to their own devices. But they at least do make sure they don't starve and pee themselves, and do magically hear and act on the cries of babies and toddlers even if these are in a different room and/or on a different floor. Children do not get taken away with high free will on.
My Alvi family is always on high free will. There are now 7 in the family plus 2 cats. Hunger and bladder needs will take care of themselves when the Sims are at school or work. Hygiene is not a critically important need to maintain. Low energy solves itself by the Sim collapsing where they stand and cannot result in death. Low social need cannot either. Hunger has two levels that run the course of 48 hours as far as I recall. A Sim will drink water to fill their hunger if food or cooking is unavailable. They will not starve to death with high free will on and a sink available.
So, as much as the illogical ways of Sims frustrate and worry us, they actually
can take sufficiently care of themselves. Just not in the way we could. And promotions at school and the job might take a little longer if the Sim's mood is a bit low due to low needs.
Hope this helps you worry less
