Normal cycle alternates between rotating the drum slowly and pausing to tumble the wash, I use a cool synthetic was for most things and a hot cotton wash for towels, and never have a problem with the machine getting mould or smells or whatever.
I'd never used wool mode before, until I noticed non-iron shirts suggest being washed on wool mode, so I did. It turns out the wool cycle rotates drum very briskly non-stop, no doubt to "pin" the load against the drum and stop it stretching etc.
However the brisk rotation manages to dislodge *so* much fluff from between the inner and outer drum it absolutely coated the shirts ... I tried running several full or empty washes, boil wash, with or without washing machine cleaner and/or detergent, probably 10 washes in total and I could *not* stop the wool cycle from dislodging this fluff - hence I just won't use it again.