Secrets of Rodinal Stand Development:
1. Always pre-soak. It doesn't matter if it is voodoo, it's good voodoo, so just do it.
2. At 1:100, you can only develop 1 roll in a 2 roll tank lest you risk uneven development due to insufficient developer in the solution. Violate this rule often enough, and you will eventually know what I'm talking about.
3. Agitate, vigorously, for at least one full minute. Invert, rotate and whatever else you can think of. Do them all.
4. Don't, don't touch it for at least an hour. Go have a beer or a coffee down around the corner.
5. With most slow films, and this works best with slow films, you'll get .5 to 1 stop push in the shadows and muted highlights. Expose accordingly.
6. When you've mastered all of the above, go back to using Rodinal 1:50 with normal agitation.