Whether it was my Thiers-Issard 5/8 or Merkur Progress, I would always get nicks and irritation if I tried a single pass with the grain plus an additional pass against the grain. I don't know if it was my technique because I'm fairly new at this, but I would shave very meticulously and still get irritation and nicks. I would even use top-notch stuff like the Art of Shaving soap AND pre-shave oil.
My skin didn't look nor feel good at all. That alum block did a great deal of sting, too. Well, I only shave with a single pass with the grain now. Even across the grain is pushing it, as I still get a nick or two.
Anyone else like me who only does a single pass with the grain?