Why Don't All Dogs Shed at the Same Time?

A couple of weeks ago I had a nasty issue with white hair all over the house as my cream lab lost his winter coat. Bear is a BIG dog, so when he starts to loose his winter coat we end up with two or three more labs running around the house until I can catch them with the vacuum and evict them.

Last week, just as I was able to breathe without inhaling dog hairs once again, Beebe decided that it was time to loose HER winter coat. It has started all over again, but thankfully Beebe is about half Bear's size and her coat is much less dense when it sheds. I only seem to be getting one spare dog in the house from her.

I'm not sure what it is unless it was how much hair Bear had was why he lost his coat earlier than his mother lost hers. I think it would have been easier on me if they had lost it at the same time, rather than stretching out the need to vacuum everything several times a day every day for a couple of months now. When Bear shed I had to vacuum the carpet in the living room every few hours. I would have kicked him outside, but it was still dropping below freezing when he lost his coat. I couldn't do that to my dad's Polar Bear.