These tend to be, in a 30 minute slot:
<2 minute highlight reel>
<2 minutes of original footage>
<1 minute of "coming up next">
<5 minutes of ads>
<1 minute of "previously on...">
<3 minutes of original footage>
<1 minute of "coming up next">
<5 minutes of ads>
<1 minute of "previously on...">
<3 minutes of original footage>
<1 minute of "next time on...">
<5 minutes of ads>
Which gives 8 minutes of original footage stretched over 30 minutes, with 15 minutes of ads and 7 minutes of rehashing.
This format, although now popular in other countries, is a "modern-classic" of US television.