I'm finding that the socks are not the greatest solution either. I used to use fire blanket wool and kapton which although messy to install would last for a long time. It could not fall off the nozzle at all. I'm finding that the sock slips down a bit no matter how far in the nozzle is to the heatbreak. It has started to rip at the nozzle but I'm not fussed. it is advertised as disposable and has a price to reflect that.
Fair enough. I'm certainly not condemning them for trying, and you're dead on regarding the low price of the socks. It's just a bit painful to have such an obviously awesome solution work only half the time. I'm hopeful they will continue improving this as they do with everything else.
After a few prints, I remove the sock and clean the nozzle while hot, as there is some pickup leaking back between the sock and nozzle that accumulates and pushes the sock down slightly. After refitting it's all back to normal.
Can't remember where I saw it, but someone had a loop of wire around the top edge of the heater block to make sure either the sock didn't slip down, or to keep it pulled up tight against the nozzle.