Twice the length from the middle to the end...apparently
I think the key is to have a very gritty growing medium for aeoniums. That way, you can water more freely but excess water will get away from roots.
If you click on this thread and scroll down http://www.gardenersworld.com/forum/talkback/visit-the-old-vicarage-gardens-east-ruston---friday-5th-june/719339.html you'll see Wonky's photo of the aeoniums at The Old Vicarage Gardens East Ruston in Norfolk. They're outside all year round, protected in the winter from the bitter north-east winds by some great shelter belt planting