Would it help if you used the front rings as a sort of ballpark gear and fine tuned with the cassette? So, if you're in the big ring and it's getting harder, or steeper, or you're losing momentum, change to the small ring first. And if you're in the little ring and you're getting faster or you're spinning out, change up to the big ring at the front first. (There's some possibility of temporary crossover, I suppose, but it's unlikely that there will be heavy strain on the chain. ) I think that's what I tend to do though I've never really thought about it. And I've done night rides with a bike that has those indicators on and I've never missed them.