At allegiant we have all CFMs and our fume events are fairly rare. We had a spate of them about a year ago after the company started a mitigation program, but that died down after the few month. I strongly suspect that the higher the level of awareness the more reports are received. For a while, we had FA's calling up front with possible fumes every time someone farted or took their shoes off. I haven't personally smelled a sustained dirty sock smell from the packs in a very long time. We switched to Mobil jet oil and they quit over servicing the APUs. That seemed to make a big difference. I used to get it maybe 2-3 times a year. Usually on idle descent into a humid place below 10000.