5 hours from filling the kettle with strike water and start heating it, through weighing and milling grain, until pitching the yeast. That's for 5 (or 6) gallon batches, and does
not include cleanup.
Since I usually brew 2 (sometimes 3) 5-gallon batches back to back (with an hour or 2 nap in between, now), cleanup is only once. But yeah, cleaning takes about an hour.
Here's an example of one of my (in)famous brewnights, with timings of various sub-processes. 5 hours on the dot (before cleanup):
https://www.homebrewtalk.com/threads/3-day-ipa.674733/
10 gallon batches would only take 1-2 hours longer, due to extra time needed for heating and chilling, everything else remains pretty much the same. But, I don't brew those very often anymore, unless I split them before adding late or whirlpool hops, which can save some time.
The past year I've been splitting 6-gallon batches in half for more variation, such as different hops and/or yeasts.