Getting Tuned During Winter Months

subaru’s when tuned keep most of the stock info on there correct? Unlike hondata or something where you import as much of the stock data as possible and use that as a starting point?

I ask because I think the real questions are: how much can the ecu adapt after being tuned, and does the tuner have to set them up properly to adapt from the tuners new values to other values which will still hold the AFR at the correct amount.