To improve the preservation performances it's better to leave the cryotubes containing the fungal strain under glycerol at least for one hour at room temperature, then proceed with a gradual freezing. In this regard I suggest you freezing boxes such as those reported at:
what about other (not only yeasts) - filamentous fungi for long-term storage? Do you cultivate them in liquid media and then add glycerol (mixed) and freeze?