A rule of thumb on shifting on bicycles is do most of the shifting on the right (the 1-8 in your example). Rear derailler shifts are crisper and easier to execute and the result in smaller differences. I would say that most cyclists do over 90% of their shifts on the right.

The left shifts are for more major changes. Sort of think of the right as adjusting and the left as setting the scene. On a triple, I only get down in the small ring (the 1) on the left, on nasty hills. For moderate speeds such as moderate climbs, headwinds and so on, I am in the middle ring (the 2) and for higher speeds I am in the big ring (the 3).