closely monitored and dropped the 5F per week. Constantly adjusting it as the temp changed outside.
Turns out chicks are a lot easier than that. Shine the heat lamp in a corner. If they never leave it, they're too cold. If they never go under it, it's too warm. Once feathers cover their body, they're good. The end.
You can fail on the safe side by putting the heat lamp too low (IE, too warm). They'll just sleep on the edge of the heat and you'll know it's too warm. That same principle means you don't need to worry about constantly adjusting due to changing outdoor temps.
Keeping the food and water a little elevated so they can't walk all over them will keep them cleaner.