Engine flush... Yes or No???

Many years ago i had a 68 chevy pickup. It was sludged up so bad i couldnt pour a quart of oil onto it. I pulled valve covers, scraped out what i could. Replaced valve covers and poured in a quart of “gunk” engine flush. Kicked it up on the fast idle cam and let it sing for about 3 times the reccomended run time. Dumped the oil, and replaced the standard filter with a 2qt size without a bypass. Drive it a couple weeks and changed oil again. We ran it for years, then i installed it into a 77 jimmy and beat the snot out of it. It ran suprisingly well. I will say i got lucky. Would i engine flush again? Good oil pressure and no knocks, sure.

my 51 dodge flathead got the oil pan pulled 2x and cleaned. Its on its 3rd oil change in a couple hundred miles. 40 psi and runs mediocre. Figuring some oil additive would free up the rings in number six. Nah. Its coming out.