I had to put them about 4 inches apart to hold my HDMI cable in place.
Being 12 inches apart they wouldn't stay in place. They are small and certainly cheap, so go ahead and buy some because they are acceptable if you use a bunch together.
Heavy Duty 8 Inch Nylon Self-Locking Cable Zip Ties - 100 Pack In Black
52 Review
25 Pieces Desk Wire Organizer Cable Ties Zip Ties Adhesive Cord Clips Cable Management Cord Keeper Desk Wire Management
25 Review
2-Pack 16In Under Desk Cable Management Tray - Metal Wire Mesh Holder For Desks, Offices & Kitchens (White)
31 Review
50Pcs Adhesive Cable Clips, Cord Holder Wire Management For Car, Office And Home (Black)
42 Review