why would you only partially extend the sections???
speed.
Some times I extend sections half way, some times a 1/4 sometimes fully it depends on the house, it is like saying why use a large 18/22 inch squeegee on 5 meter panes of glass when you could use a 6inch, the simple fact it is quicker to do some times.
winpro before you jump in I have not tried the extreme as yet but there is only so fast one can go the pole weight of an slx I am totally happy with at the heights I do at the moment, I am quick, it is the way we use tools that make us quick or slow also the experience we have using the tool.
So before someone jumps in and says you need to fully extend or do it half way, please remember the reason why your making this comment