Not necessarily. It depends on why the offspring couldn't crawl or walk for longer. If it's associated with something that increases survival in mature members

Not necessarily. It depends on why the offspring couldn't crawl or walk for longer. If it's associated with something that increases survival in mature members of the species, it might be tolerated, even selected for. For example, if the child is delayed in walking because more metabolic resources are being channeled to larger brain development, that could be a survival benefit. I use that example, because that's essentially the theory of what happened in humans, in comparison to chimpanzees. (Obviously not 1 child randomly taking 2x or 3x to develop, but a slow evolutionary process.) Chimps are relatively helpless when they are born too, relative to most species. They nurse for years, stay with parents for years, are totally reliant on them for survival, etc. But they are not so helpless as humans. It's estimated human gestation would have to be about 18 months for newborns to be at a comparable stage of cognitive development as newborn chimps. So, from this perspective, we do take 2x the time in comparison to chimps, and yet it was tolerated. I guess my overall point is that evolution is more complicated than how quickly an offspring can crawl or walk or be independent.