I use one of those 2 or 3 gallon bucket cloner and use Clonex, as long as the plant was healthy, and the water temp is right, i rarely get clone failures.I had the same issues with a strain I can't remember, always took a week or two longer to root.
I did cuttings as a job, ie thousands per week.
It works better when you use soil or slightly fertilzed sand (or whatever I guess - rockwool, cocos etc), then they don't suffer that much. Or I sometimes dip them in a fertilzer solution i have around when I see them suffering.
Some may take a couple weeks or so to root, while others root within a few days.