Heard time and time again people say they hate using ladders for tree work. Personally I can't imagine not having the use of a set of ladders They literally have 101 uses. I'll chuck a few out there, please feel free to contribute.
Access
An obvious one. People argue you should just get better with a throwline....rightio....what about a tree that is nestled in a stack of brambles, blackthorn or other nasties. The nearest you can get to the bottom of the tree is 15ft and theres no limbs overhanging that you can ping a throwline over.....Ladder bridges the gap and you're in the crown while throwline boy is still faffing about and getting himself in all sorts of muddle with the thorns.
Tip reducing smaller trees
I often end up doing a lot of these type trees off an a-frame and utilising a set of poles(wolf extendables with lopper attachment). Far quicker than trying to get out on whippy ends. I am typically talking about little 20-30ft trees. If I am over staffed on a job where there is multiple reductions though I will often reduce enough of the crown to a point where the remaineder can be done from ladders and poles, leave one of the guys to finish off the lower crown while I get straight into the next tree and crack on with the climbing.
Crownlifting/single branch removals
So you have to remove one single limb from a tree which is out of reach. You are welcome to get your throwline out, climbing gear on...personally i'm throwing the ladder up there, cutting the branch off(Whilst tied in, paying special attention to position the ladder in such a way that the branch does not hit it and dent one of the rungs), then drinking a cup of tea while you are still getting set up
Setting pull lines
I will often use my throwline for setting pull lines. On trees where its not possible to isolate a limb I will just hurl it over through any fork and tie it off on itself at the base of a tree with a running bowline. However sometimes putting a ladder up to put on a line is far quicker and easier, such as when pulling over a row of Leylandii. The other advantage of this is anyone on the crew can set a pull line in a tree providing they can tie a suitable knot and aren't scared of climbing up a ladder.
Ivy removal
Again, if there is a job which is entirely ivy removal I really don't need 2 guys on the ground watching me tediously picking away ivy off stems. I can send one man ahead to the next trees removing all the ivy he can reach from the ground, and if there is still not enough work to get 2 men going with the clear up he(or she) can proceed further up the trunks using ladders to a height he's comfortable at.
I'm sure theres plenty more but if I list everything the thread will be over, but to sumarise ladders absolutely have their place in tree work for me personally.