Lee
Get rid of the barrels and change over to a 250 or bigger tank, use 100 metres of microbore hose instead of the garden type.
Try to leave the hose reel on the van if you can speed you up a bit.
Wfp all the windows, you can still blade the bottoms dry if you want, but you don't need to.
On 1st cleans have 2 brush heads on hand, use the 1st brush to remove most of the muck them finsh off with the 2nd and clean brush.
Start at the back of the property first and work your way to the front, when you have cleaned the front, go round the back to wipe the botton sills down, you can then check how the windows have dried, if any spots or streaks are showing then either squeegie or re-apply the wfp to them.
If customer offers you a drink, then drink this when you have finshed cleaning the windows not before.
Having 2 men on 1 property does not speed you up at all, unless its a very big building.