i have been thinking about this topic for few days since i found bunch of grey mold in my Panache cuttings. during the start of rooting season, i check my cuttings almost every other day, sometimes everyday. during the check, i would make sure the bag is ventilated, and that the cuttings are not sitting in a pool of water.
Panache cuttings, and also i forget which one, but some cutting sometime ago were left in the bag for about a week without ventilation and moisture level. they both molded very heavily.
i think, at least for me, checking the cuttings at least every other day and making sure they are ventilated, and moisture level is not too high would help with mold and what not. by the way Panache cuttings are coming around. i think i caught it soon enough that washing them off with AB soap helped. starting to see few roots pushing out.