not true. unless you are jobless or a stay at home mom, life gets in the way. most people work 8 hours. some days there are errands to do. other days there are obligations like birthday dinners or nephews bball game, etc. other times you are just injured or too sick to go anywhere.
my 9 month old working line does just fine without exercise on certain days. in the summer i exercise him every day. sometimes i'm out with friends all day and walk him at midnight. in the winter i can go a couple of days without exercise and he's fine. iit's not really about exercise but about keeping your dog's mind stimulated. there are better ways to play with your dog then to walk/run it in severe weather.