Well I've given you the figures outside which our crews must "legally" recalculate performance (B738), they're hard numbers and I think they're important, while there's no replacing basic judgement calls from the LHS, it removes the option of "yeah the temp's gone up 7 degrees, but it's a 4km runway, we'll be totally fine", which in my opinion is the first hole in the Swiss cheese, and every Captain has their own "comfortable limits", some a lot more "comfortable" than others. Not sure if these are operator or Boeing figures.
We never blindly punch in the ATIS figures without consideration. For example, if the temp is 10 degrees but it's 9am, we're not departing for 30m and the sun's blaring, we'll use, say, 14 degrees, which gives us up to 15 before a recalc is required.