Boring is subjective though. For some like me the ideal weight gives endorphins where as too much feels like cortisol. Too light is sort of nothing. So I aim for that "yeah I pushed something" feeling. Which isn't failure.

Let’s be realistic, everyone goes through periods when they just don’t want to work out.

So optimal in terms of personal preference is defiantly worth considering alongside optimal in terms of results, but optimal in terms of returns on effort defiantly has a place at some point in our lives.