Couple of (probably silly) questions

Soooooo I will keep it simple.

Firstly, UBIK, No Nonsense degreaser and other chemicals. Do they harm or degrade your brush over time? 

Secondly, what pole extension do you use when you only need to extend one or two sections? Naturally I use the first couple but would the thicker sections not make more sense due to flexing? Or do you alternate them to keep wear and tear down on individual sections? 

Cheers

If it's windy or the angel to the window is a on the shallow side I tend to only move the first sections out about half way which makes them way stiffer. But the poles does get more top heavy and feels more heavy over all if you don't pull the sections all the way out, so it's a trade off.

I have a gardiners xtreme 47, where each section is extremely stiff compared to all other poles I've tried.