With the '70s and '80's bikes with 5x2 or 6x2 that I've owned, the chainline seemed fine for using the small ring with the whole of the rear cluster. You sure could go all the way from the small cog to the large cog or vice versa. Might need to do it carefully to avoid stressing or jamming the chain or even jumping it off the cluster; don't just yank the lever. It was easy to develop a feel for what's ok and what's too fast. Yes, I did have to trim the front a little bit when doing that. The big ring was only good for the smallest two cogs. Big ring with the bigger cogs sounded and felt through the pedals like a crossed chain. So, for me with my only 'average' power, I am on the small ring almost all the time. Big ring is 'overdrive' for favorable conditions - tailwind, slight downgrade.