To flush or not to flush...

[Ferryman]

My brother has a 350 Yamaha and I have a 200 Verado, he flushes his engine religiously once a year without fail.
I’m a marine engineer and couldn’t sleep if I used mine once without flushing it through!
Neither of us ever has any engine problems but I still expect his to die soon.
He had a 275 Verado on his last rib and it lasted for years with his complete lack of care!