I do agree that converting is a waste of time, just use whataver unit is provided. After certain time you would get use to them. I learnt imperial system during primary school, and our government changed it to metric during my secondary. So I learnt both. I dont encounter much problem to use inch or mm now, although at the beginning it was so confusing and troublesome.
Both I deeply felt we should standardize all measuring unit, although it is almost impossible. Resources were wasted everyday because of different system. A bolt and nut store has to store at least 3 times more of stock in order to meet different specifications: inch, metric, NC, NF, BSP.....Crazy!!!! :x