Here are some things I've learned...thought I should pass it along.

If you see a flyer with advertised deals from Fri. to the following Thurs. for example, you may not want to wait until the Thursday (last day) to go in to the store. I have found that many stores run out of stuff. They don't seem to order enough for an entire week.

In the last few weeks, I have seen flyer deals for the following, but they were all out when I went in:
-diapers in Walmart, but they wouldn't give me a rain check because flyer said while quantities last
-Smart Ones at Walmart
-laundry soap at SS. They don't do rain checks there.
-toilet paper at CT.
-mandarin oranges at Sobey's...

And often I've noticed that stores advertise something in their flyer, but might not bring it in. I've seen that at Rexall and SDM in the last couple of weeks.

Lastly, make sure you take your flyer with you to the store. I notice that stores will remove the shelving price tags of items that are in the flyer (esp WM). So, people just walking in, won't pick up those items because they don't know how much it costs. FYI