I believe only having 2 sawmills with 16 points total makes blowing through the maps way to easy and short. Maybe if there was more then 6 maps it wouldn't noticed as much.
I think instead of points per se, each sawmill should have a load requirement of each length of log. Maybe 3 short log loads, 2 medium log loads, and 2 long log loads. Or maybe have one saw mill take 3 long load logs, while the other mill takes 2 of the other types.
Another idea would to have other vehicles (say they're of the same log company as you) broke down either by fuel or damage, and you have to help get that truck back to 100%, or at least driveable. Not saying to have that truck putter along once its fixed, but side objectives none the less.