Some of you will know this, but If your channel is longer than about 16", then somtimes it will benefit from a slight bend. If it was exaggerated it would look like a bow. This evens out the pressure that is applied when blading a window and helps the very ends keep in contact with the glass. The bend should be VERY slight and hardly noticeable, but can make a big difference.
Principle works on all channel types.

Good tip, ta.