One size horizontal pulls look fantastic when the drawers and cabinets are all the same width, or close in size. But most of us have varying drawer and cabinets widths. If possible, try to limit the number of different sizes and try to keep the proportion of the pull to width the same. On my 36" and 39" cabinets I have 14 1/2" pulls. On my 18" to 27" cabinets and drawers, the pulls are 10 1/2" (I have horizontal pulls on cabinets as well and love the look.) From 13" to 17", I have 8" pulls and I have two narrow cabinets (12") which are in a corner and because of the handle hitting another cabinet, needed 6" pulls. My preference is for the longer pulls as it has a more contemporary look.
Try putting measured strips of blue painter's tape on your cabinets and drawers to see which lengths you prefer.
Q
Towel bar
Q