I think the main issue with sewers is hepatitis. If I can't clear a blocked sewer with a plunger on a rod in ten minutes I call in the guys with the machine. I know from experience that you can spend hours with a full set of rods down the drain and never get it cleared properly.
The worst ones are when it's backed up a soil pipe into a block of flats etc. Yeras ago we used to do maintenance for the Burton Group. We got called out to a blocked downpipe on our local Debenhams. There was a box gutter half way down the front of the building which was over spilling we tried to clear it from the top but failed. The down pipes ran down inside a boxing and re appeared in the basement. We went into the basement and carefully unscrewed the rodding eye which was about 6 foot above floor level. Foolishly we then decided to try rodding from the bottom. As I pushed the rods up I felt a point of resistance and gave it a good knock with the rods. There was a loud rumble from the pipe and, realising we had no hope of getting the cover back on, my colleague and I turned and ran. We hadn't made it to the door when the thick black filthy water got to the rodding eye. The two of us looked like something from a comedy show. The front of us was clean and the back was smothered in black gunge.
We had to send someone out to the van to get our boiler suits so that we could change out of our clothes. Luckily the area we were in was an unused maintenance workshop. Some of the basement areas were used to store racks of clothing. It still took us hours to clean the place up though.