Are afternoon naps important for kids or they can be skipped? Do they play a part in physical development of the kid?

I think it will depend more on how much sleep your kid gets at night. It is ideal for kids to get at least 10-12 hours of sleep each day, and when it can't be done at a stretch at night, afternoon naps can help. Also, if your kid starts to get cranky and irritable during the day, it could be probably be due to sleepiness. It's true that kids grow in their sleep, so it's important to make them sleep those required hours. You can either let your kid sleep for 10-12 hours at night, or add a small nap on days when the sleep hours are not fulfilled.