for adsense for content you can have 3 ads units on the page ..... however, you should consdier structure of your site , theeme and content , its not nessessry to put 3 adsense units on the page ... there is another theory , the more ads then less paying ads you'll get .... the less ads unit the high paying ads will be placed ... Hope this helps
On any given page, you're welcome to place up to: - Three standard ad units - Three link units - Two search boxes - Three referral ad units - One video unit