How accurate is My Pet Chicken when they say how much a chicken lays?

What specific breed are you looking into? We can tell you from experience depending on what you are wanting...

 

only 1 a week? i get 1 from each hen a day! lol

 

Here's a better source than a hatchery's website to find out general information about breeds:

http://www.ithaca.edu/staff/jhenderson/chooks/chooks.html

If you'll look across the chart at the color and size of eggs for each breed, you'll also see alot of eggs in one pile for some breeds, only a few eggs in the pile for others. That's to give you an indication whether they are prolific layers or so-so layers.

I go to a hatchery website to look at the pictures of the birds and to see what they have available. I don't think you should decide what breed you want by looking at one hatchery's website. The hatchery is in business to sell lots of chicks, just like a car dealer is in the business to sell lots of their cars. Of course the hatchery is going to emphasize the good points to a breed and downplay the negatives.

By the way, I once used MPC's breed selector to find the breed that's "just right for me" because I was bored one night. Turns out I wouldn't own any of the breeds that they recommended.

 

Yes, the average number of eggs per week per chicken. I too like web site that gritsar cited.
http://www.ithaca.edu/staff/jhenderson/chooks/chooks.html

I also like Feather site.
http://www.feathersite.com/Poultry/BRKPoultryPage.html