BarbaraSue

I began using both interchangably. Then I began to notice that not all the blocks were the same. Just a smidgen off, but when it is multiplied over the quilt, it does and can add up to distortion. Mine did. It was more eveident with a block exchange.
I have turned my mat over and use the ruler to measure. I have the same company's ruler in a small square, and long ruler. I have cheked them together and they match. (When I compared to another small ruler of another company, there was a difference in their grid.)
I am not having the problems I was having. My points match easier, and I have better consistancy in my measures.
But if it works for you-- Don't fix it!:)

corgiplace

I was taught to not use the ruler on the mat. They are sometimes not accurate.

bgullett

I mostly use my ruler, but do use my mat as well.

IAmCatOwned

I do quick measures using the mat, but for precise measuring, I use my ruler.

Just check your mat measurements against your ruler. If you are happy, I'm happy.

Annya

So do I just use my rulers.I have had things go wrong using the mat( a long time ago.)