I think there are a few reasons this task ended up being so brutal.

1. I ended up with some sort of nasty cold the past few days, but I decided to push through an hour at a time straightening flanges. Any task done for 7 hours would get tiring, but it’s worse when you are under the weather.
2. The task is relatively subjective. It’s difficult to get everything perfect, so you have to decide when the flange is “good enough”. This is slightly stressful considering it can result in visual deformations on the wing skin later on.
3. The Flange straightener tool (FST) was useful, but not the silver bullet. Depending on the state of the flange before application of the tool, it changed how you needed to apply the lever. I think I ended up using the hand seamer about as much as the FST, sometimes to undo the overbending from the use of the FST.
4. It doesn’t end. There were a LOT of ribs, and each one took anywhere from 5 minutes to 20 minutes. that’s a ton of straightening.
5. Once fluting is done, it might actually revert or cause issues with the currently straightened flange. To minimize this, I forced the rib webbing flat on the table when bending, which theoretically represents what forces will be on the flange once it has been straightened. I doubt this will completely solve the fluting changes.
6. Leading edge ribs were especially challenging, and I ended up accepting some amount of non 90˚ angles. The reason is because of the curve of the rib. When I bent the flange properly, the rib became very oddly shaped, so I think I will flute and bend these at the same time.