Comment by yodon

As a conversion optimization question, I suspect Reddit would get better conversion on their "do you want the mobile app" banner if they only showed it randomly about 10-15% of the time. By showing it every time, they cause viewers to remember their "why would I want that - I don't" decision from the previous time they saw the question. Reducing the frequency would likely result in more people considering the question as a fresh new question independent of the previous viewing when presented with it the second time, increasing the odds they go with the install (by definition these are people who didn't install the first time, so their remembered decision is by definition no, so encouraging them to consider the question again as a fresh question can only improve the conversion effectiveness of the prompt over their remembered decision).