I am constantly getting Choice Hotels ads that actually prevent me from seeing the text of what I am trying to read or type. The ad scrolls with the screen so the only way to access what is below it is to sequentially refresh until a new ad is presented that doesn't intrude. This really sucks.
The ads seem to rotate based on time, not on refreshes. If I see that ad (or any other ad) and hit refresh right away, it reloads the page with the same ad. I can hit refresh a bunch of times and still get the same ad. If I wait a minute or so and hit refresh, I get a different ad.
A few minutes later it will be back. I normally get the ad several times in one session. I can come back for another session later in the day and see it several times again. I haven't counted, but it shows up every few page views.