How to optimize ad placement for maximum revenue?

[SocialBee]

Where should I put ads on my blog? top, middle, bottom? How many is too many?

[LenaVlogs]

Tested a bunch of layouts. this works best:

desktop:

• sticky sidebar ad
• one ad after 2nd paragraph
• one ad in middle of article

mobile:

• after first paragraph
• middle of article
• end of article

went from $4.20 RPM to $5.96 RPM just from better placement

[RisingAdmin]

I ran an experiment

lots of ads: made more money first month but traffic dropped over 6 months
fewer ads: made less at first but traffic grew and ended up making way more

too many ads pisses off readers and they don't come back

I use 3 ads per post max now