I ride in the rain a lot and stick it on 3 in those conditions. I run 55 profile Michelin Road 5's and to be honest, I'm not entirely sure how much it takes to make the TC light come on. On the 50 profile OEM D214's, it would come on all the time on setting 3 in the dry when pressing on in the twisties . On 55 profile Metzler 01's, it hardly ever came on and it's probably a case of not even noticing now. In drier conditions, I normally leave it on 2 apart from sticking it on 1 for a track day session. Didn't seem any different from 2 but that's probably because I run out of talent way before the bike!