The way I understand the cloning drift, it's a problem with DNA/RNA repair at the cut sites of both the mother and the clone.

Obviously the plant is stressed when it's cloned, and some of its normal life processes can malfunction, introducing mutations to the DNA. Mostly they will be unnoticeable, or if they are major, the cutting might just not survive, so you wouldn't notice...

But over a long period of time the sum total of all those small mutations can build up to the point where the grower would notice drift.

Anyway that's just how I understand it, and why I'd be more likely to keep just a couple old mothers, and regenerate them only every coulple years, rather than clone-of-clone-of-clone...