My experience is that young pilots starting out are weary of ice for a few hundred hours, and then once they have had trace ice build up and do very little to the performance of the aircraft a few times they get a bit bold and tend not to do that 180 turn straight away. Then one day the trace ice turns to three inches of rime in about 40 seconds and the airspeed indicators don't match and the airspeed drops way back .....then they rethink the 180 turn thing for their next flight. Human nature I suppose. It's like they (me included) have to see it for themselves before they'll believe that it can be scary stuff.
At the end of the day, if you have no anti or de ice and you can see ice building, get out of it.