Hi. Coming at this thread late as I've been mostly offline for the "holidaze".

I often steer my roasts in 'real time', even when using a background profile from a previous roast. There are often subtle changes in ambient humidity, temp, etc, between roasts where blindly following gas settings from a previous roast doesn't guarantee me the same outcome. I've found that following delta ET (yes delta ET) on my roaster tends to indicate where my other probes will head next, so I keep my eye on it more during a roast. I will often tweak when a gas setting happens (vs the background roast) based on delta ET to keep my overall desired targets/curves on track. e.g. I might drop the gas a bit sooner vs. the background roast if I notice the delta ET plateauing or starting to spike. I find this gives me a higher level of repeatability with my roasts.

*Disclaimer: I use a solid-drum Huky roaster with RTD's and minimal smoothing settings in Artisan. The Huky also has low thermal mass which may allow it to respond more quickly to ET probe changes, so my technique may not work on other roasters/probe hardware. YMMV.

I do the same as Brewzologist, Delta ET is a reasonably predictor of what is to come in BT

^^^^^^^^^^^^^^This