I have shot many deer on the flat out run most of the time ahead of dogs or jumping them in the swamp.Thats how we here rifle hunt.
I have never lead any of them no need too. if your leading to me its to far of a shot and (BUT THATS JUST ME)
there is a trick to use no matter if you are using scope or iron sight, it was tought to me my a fellow who has passed on now at the young age of 90, he always said when you see the deer and as long as the cover allows it you can pretty much tell where that deer is going to go
when you determine this you pick a spot where it is coming through
somtimes it is a little opening or past a clump of trees anyway when you have the spot picked and you may have to change it a couple times before the shot happens but when hair hits your scope or your site pull the trigger and you will be succesful alot mind you this isnt a garantee
as there is a lot more air around them than what they take up
That is how I do it and I have had more success than not!!