The recipe I have does take about 3 days, but it's mainly about the small steps you need to do to laminate the dough. Actually cutting and frying the cronuts is the easy part.
That is exactly right. It really isn't as hard as ppl assume when they hear 3 days. It's just technical. Plus it has a few different components. A filling, a glaze, a sugar to coat the outside (that last thing takes almost no time tho). You also have to make a butter block. Everything has to be even. You have to be careful not to tear the dough. Also, if you don't have a deep fryer, you need a good thermometer and the frying oil has to be kept at a consistent temp. The butter will burn while inside stays raw if too high and the outside won't be crispy if too low. Most doughnuts don't require as high a precision level.
I highly recommend ppl try this if they enjoy challenging cooking. The flavor of the dough is incredible due to the butter and long fermentation time. The texture is unique and really amazing. Results make the effort worthwhile.