Glad the re-fire was a success!
Yestreday I did a glaze fire and it came out perfect with the 8 hour shut off... today.. not so much!!!
Are you controlling the kiln shut-off entirely with a timer ? As you're discovering, it's going to be very difficult to get consistent results that way. There are a lot of variables that can influence the time it takes your kiln to reach a given temperature and/or cone stage. How full and/or how densely your kiln is loaded can make a big difference. A kiln loaded with several shelves full of small pieces will take a different amount of time than one that's fired with just one or two large pieces. (Even voltage fluctuations in the electrical supply can affect the temperature generated by the heating elements.)
You don't have to have a fancy computerized controller, or even a kiln-sitter, There are several folks on here with way more experience than me, who fire without either - but - just like baking a cake, or grilling a steak, you need to know more than "how long has it been cooking", to properly determine when it's done. They use witness cones, pyrometers, and/or have many years of experience that lets them judge the temperature of the kiln based on the color they see through the peep/vent holes.