Oh man, that reminds me of the year I tried to put up a simple shelf. Measured everything twice, got the level out, and it still ended up looking like a rollercoaster. Sometimes the simple jobs fight back the hardest. I spent more time fixing my mistakes than the actual hanging.
Three tries to hang a flag seems like a lot of effort for a piece of fabric. It's just a decoration, not a national monument. I guess some people really get into that stuff, but I don't see the big deal.