I taped all my sessions and had them transcribed, so not only do I know how long I ran over (sorry!) I also know how many words / sentences / paragraphs were contained.

See E-Commerce Optimization slides and E-Commerce SEO slides

Both "15 minute" sessions ran 22 minutes

Both sessions had the same number of words (~4800)

SEO = More tactical = More Slides/Ideas

E-Commerce Optimization = More strategic = Less Slides/Ideas