Well, no-one else has offered so here goes.
I generally keep the oiler on high, even with a 16" bar, in fir or oak. I don't think this is a big waste as it keeps my bar in good condition.
If you think you are wasting alot of oil with it on high, turn it down a bit.
The general rule is:
Softwood and/or small bar, a bit less oil is needed.
Hardwood and/or large bar, more oil.
You are the best judge of your saws condition. Between cuts, turn the saw off and lift the chain from the bar groove and check for oil. Watch the chain for any discoloring or smoking.
If you use cheap oil it won't hold to the bar as well and so you will need more, which still might not lubricate properly.
Hope this helps.