Don't live by idioms. That's been ingrained in me too, always recalling Doyle's admonition not to chase flushes and straights. But it's an over-simplified slogan that does not recognize the complexity of the game. It's fine with me if you and pOK live by the idiom, because we need opponents with those kinds of holes in their games. pOK seems to offend a lot of people and he's constantly berating the "flushers." Fine. Never chase a flush.
Ignore the reality of odds and pot odds, and ignore the fact that there are even times when your trailing hand is favored to win by the river.
It's not my intent to insult or berate you. I'm trying to be helpful. If analytical evidence supports a flush or straight draw, it's simply the correct move in spite of any idioms, slogans or "gut feelings." Simple facts.
Gary the Worden