[Beagle8U]

The 48 min. for personal time, (either paid or unpaid) comes from US labor law governing assembly line workers.
10% for personal time must be granted.
For non assembly line workers you must allow one 15 min. break every 4 hours.

Damn few companies offer only the minimum required by law, and seldom enforce their own rules unless they are being abused.
Laws vary from state to state, those are Federal minimums.

[Willie Green]

For non assembly line workers you must allow one 15 min. break every 4 hours.
Damn few companies offer only the minimum required by law,

Actually, the federal minimum is 10 minutes.
Perhaps there are some states that specify 15
and I'm certain there are individual companies that offer 15 (either as a generous perk or as a contractural concesion.)
But over the last 30 years that I've worked as an industrial engineer, setting labor standards in 7 different factories in 6 different states, every one of them had 10 minute breaks.

Damn few companies offer only the minimum required by law,

That's true as far as actual wage-rates and benefits go,
but actual time on the clock is a different story.
But then again, my experience is with more mature, smokestack industries.
Perhaps high-tech manufacturing became sloppy back when they had money to burn.
It wouldn't surprise me at all to learn that some Kalifornia Komputer companies maybe took a more laid-back approach towards their workforce.

and seldom enforce their own rules unless they are being abused.

Yeah, that's a problem no matter where you go.