I stand developed a roll of Tri-X shot at 1600, and all the shots came out amazing! Souped the roll for 1 hour in Rodinal diluted to 1:100. I inverted the tank repeatedly for the first 10 minutes, and then I inverted the tank three times at the 20 and 40 minute mark. The roll came out nice and contrasty. I didn't even have to adjust the levels much (if at all) when I scanned the pictures. Here's an example:

I, confident as hell, went on to try stand developing another roll Tri-X shot at 400 with the same process, the same diluted developer from the same bottle. The roll came out underdeveloped: the emulsion was a lot thinner than it should be. I'm not sure why. I know temperature shouldn't effect development too much (at this dilution). Did I forget to shake my bottle of mixed Rodinal, and all of the developer settled to the bottom? Should I have agitated it more? I would've presumed a roll exposed at 400 would need less agitation, not moreóbut I'm new to all of this.

Here's an unadjusted example of my failure:

Any thoughts would be appreciated. (: