Is the "real value" in making markets efficient something we should strive for? It's clear that not all efficiencies are good for humanity; doubtlessly the work

Is the "real value" in making markets efficient something we should strive for? It's clear that not all efficiencies are good for humanity; doubtlessly the working day could be longer and this would be more "efficient" than having that time to rest, and slaves are more efficient (considering labour input as money is much closer to zero for them, and labour output is higher).