GOOD QUESTION about Banner Ads

Simple Gamer Arts

So I read somewhere that banner ads (320x50) only need 2 seconds of viewing-time for it to count as an impression?

So my question is, should I create a logic that destroys and re-spawns my banner ads every 5 seconds? in other words, are you losing money by having a banner ad just sit there through-out the game instead of creating a logic that restarts the banner ad every 5 seconds or so?

What is the truth behind these banner ads? do you get paid more for having it sit there 1 minute vs. 3 seconds? or does it all equally count as 1 impression at the end? and therefore you should have a logic that restarts these banner ads every 5 seconds because then you'd get 12 impressions in 1 minute vs. 1 impression in 1 minute.