Does anyone really do this to their cooling system?

Without pulling the block drain plugs (or plug on /6), you'll never get most of the sediment out of the block. As someone else mentioned, use a high-quality 6-point socket (9/16"), or your chances of rounding it off increase substantially.
I've owned my car (original 318) for 4 years. Never overheated but temp would rise uncomfortably high when climbing a long hill & always had a little bit of coolant "purge" or boil over after shutting it down hot. 2 years ago I pulled the block drain plugs (who knows if they were ever out prior) and did a thorough flush. I did have to dig through crusted sediment behind the plugs. Removed heater hoses & T-stat. Using a short piece of 5/16" steel fuel line tightly inserted into a length of fuel hose, I back-flushed the block through the drain plug holes. Alternating between them, the heater hose outlets, radiator & T-stat opening, I was a bit shocked at the amount of sediment I got out of it. Haven't had an issue since - also changed to a 180* stat, added a reservoir for a closed system, and "Dex-cool" long-life coolant.