You can put limiters over your tree farm that can prevent the giant trees.. For oak, I believe setting the limiters at 8-9 meters above the saplings will stop them.. Limiters are a row of blocks above the sapling that cause the tree not to grow higher than that point. I usually set mine at 9-10.
There's always that single branching log... just sitting there.. and you never notice it until a week later when that canopy is still floating... I always limit mine at 9 blocks, which allows me to chop them down from the ground completely