I LOVE to use the walking foot on my sewing machine (also known as an even-feed foot). I've gotten questions over the years about why I am using it for one project or another. So here's the (kind-of) long version if you want me to share all... Then I'll list the situations where I like to use it most.
For a video of how it looks like please click the link below:
The walking foot is a specialty sewing machine foot that costs more than other feet and can take some fiddling to put on. There is a little bar that usually fits over the needle tightening screw. If you don't put it on right it makes a terrible noise and you'll know something's wrong, lol.
So I wouldn't go to all that effort if I didn't think it would be worth it (i.e. solve a sewing problem that arises because of all those layers or the type of fabric used). In general, a walking foot makes sewing thick layers easier because the presser foot on top of your fabric moves (or walks) too, in addition to the feed dogs underneath. In theory, this means that the top layer will move at the same speed as the bottom and middle layers.
Here are examples of situations where I like to put on the walking foot before sewing:
The walking foot is a must-have accessory for straight line quilting because it keeps the layers together and prevents the top layer from getting pushed ahead of the middle and bottom layers. This prevents puckering and tiny pleats from occurring when you change the direction of your quilted lines. I use the walking foot whenever I am straight line quilting, whether for a quilt, mini-quilt, tote bag, basket, or anything else.
If you use a walking foot when sewing on quilt binding (or mini-quilt binding), it will keep the top layer of the binding from shifting ahead of the bottom layer, which causes puckers and wonky binding. Easy fix.
Have you ever had strange ripples down your straps, maybe because you switched the direction of stitching. Well, use a walking foot and that won't happen.
This includes tote bags, wallets, or attaching thick sew-in interfacing (such as ByAnnies Soft and Stable). If my presser foot seems to be pushing the top layer instead of moving smoothly over it, I'll often switch to my walking foot.