I do this. All my FireWire 400-to-800, 400-to-400, 400-to-dinky little Sony 400, etc. cables were all in one box, the FireWire 800-to-Thunderbolt adapter was in the box with my Thunderbolt cables and adapters, and I still didn't find the FireWire 800-to-800 cable I needed to use Target Disk Mode on a friend's Mac a few months ago until a few weeks later when I was cleaning out my storage unit and found an unused FW800 cable in a box I guess I was saving on the off chance that I needed to return a 15-year-old LaCie RAID enclosure that was shucked about a decade ago off for warranty repairs.