After sewing with an industrial walking foot machine for my upholstery business, I'd never want to go without the walking foot attachment for my Janome 6500. I use it whenever I'm not attaching piping.

For those who may not understand the walking foot - it makes your layers move at the same time.

A piping foot is my 2nd most used foot - I use it whenever I have an application that uses piping (or welt as it could be called).