So on one hand, I see the argument. Simply opening unknown code, and making a change no matter how small, is a risky game. You need to research the impacts, test, and walk slowly through a deployment you haven'y done in ages. I totally get that.
But I also see the other side. Why DOES it take 8 hours to do a simple one-line code change? That's ridiculous. Somehow, we've developed these fragile systems. We've trapped ourselves in processes that add 7 hours to any change we make, no matter how small.
The status quo does not need to remain. It should be easier to make small changes. It should be cheaper to respond to simple requests. The client is actually right to question us when they just want an email to appear a day earlier and it costs them $1500.