I recently installed a lot of catenary masts, often on sloping landscape. Getting the poles all perfectly vertical can be tricky so, since I have laser levels I decided to use them. I am in the very fortunate position to have two, allowing me to direct both lasers onto each pole from different point in the room. This allows me to bend the pole to a good vertical position very quickly.
Here a Sommerfeld mast can be seen with two laser lines in vertical planes shining on the mast, showing that the pole is now vertical.
I know most people may not have a laser level, never mind two of them, but if you can borrow two and use them to straighten all your poles and signals in a day you can save a lot of time.