Excellent Weezard and it made me start thinking about Auxins and I recall that excessive amounts of Auxins, especially IAA (which is basically what "rootone" is) inhibit root elongation, but stimulate root production. So, you get initiation of a cluster of many tiny roots initially, rather than actively elongating forms. So its probably a good idea to flush the medium your in once adventitious roots initiate. This would also explain why your method works best, because the plant is directing the proper Auxins to the proper places. Even with my Salvia I have better luck just rooting in water than using rooting hormone and rockwool and all that fuss. I get lots of long roots. I also hate this idea of cutting the leaves in half. I've done it and had success, but why on Earth do we want to add yet ANOTHER stress to what this poor little cutting must endure. Humidity up, light down, leaves ok.